Minecraft Wiki:Issues

This page's purpose is to list all the bugs in the PC Minecraft version that players have come across. They pertain to the unmodified, unhacked game. Most of the single-player bugs also apply to multi-player.

Version history also contains newer bugs that may not be listed on this page at the moment.

Bugs and feature requests can now be logged at Get Satisfaction: Mojang.

'''Make sure that your bug isn't already listed in this page! One report of each bug is already enough, no matter in which section (SMP, SSP, SMP&SSP) it stands. This page is way too big to have double reported bugs standing in it!'''

Bug Labels
''Major bugs will be labeled with [!] before it. Bugs that can crash Minecraft or a server will be labeled with [!!] before it. Minor bugs reports will be labeled with [X] before it. Possible bugs/features that you and the community (on the discussion page) are unsure about will be labeled with [?] before on this page.''

General

 * [!!] The 1.8 update required OpenGL 1.3 or better to run.  Computers running older versions of OpenGL will receive a black screen on loading any world file. Mainly affects Mac users running 10.5 or older, and some Windows XP users.


 * [!!] When new chunks generate or unloaded chunks become loaded, Minecraft may crash sometimes. If it does not crash, it can cause massive lag spikes. This was most noticeable in 1.5 and down, wasn't present between 1.6 and 1.7.3, but came back in 1.8.


 * [!!] On Windows XP systems with less than 1gb of RAM Minecraft causes a fatal crash (EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000084c1) in Java versions 6 and 7 after less than 5 minutes  of entering a world (regardless of whether graphical settings were lowered or additional page memory has been assigned). The issue affects all versions 1.8 and up. A possible workaround is disabling sound, or using sfPlayer1's soundsystem fix, which prevents minecraft using up to 200MB more RAM than has been allocated when sound is on.


 * [!!] Huge memory leaks on Linux.


 * [!!] ATI users with 6.x drivers will not be able to run the game at all.


 * [!!] The renderer occasionally "conks out" leaving the user with the dirt background or a black screen. If the user has the dirt background and attempts to do anything, it will then give the user a black screen. If you tab out, or try to click or press keys, it will crash.[!!]


 * [!] Users with ATI x300/x600/x900 series graphics cards will not be able to play the game. It will freeze before the Mojang splash screen then display the "bad graphics card" error. However it has been confirmed to run on some x300's.


 * [X] When the game is paused, the hunger bar will continue to rumble.


 * [X] If you're in a boat, then you save and quit, then reload the world, you fall out of the boat.


 * [X] Endermen in caves are sometimes stuck in walls.


 * [!!] Whenever some Windows users lock their computers by either using "Start -> Lock " or a keyboard shortcut, and then log back in, the game window will be completely black. This can only be fixed by closing the engine or toggling the game between maximized and windowed settings.


 * [!!] Sometimes you will experience extreme lag, placed blocks will become invisible, and the game will crash shortly afterwards, with the "saving chunks" screen. [?]


 * [X] Sometimes you can see through everything; this randomly happens on all games on all platforms. Toggling the fog distance will change everything back to normal (Default key is F3+F).


 * [X] Rarely, the game can think you are 1 block high while in water, and permits walking through water as if it was air. Your view will not be affected in both first and third person, but if you are in a one block deep water, the underwater screen shows and you may drown.


 * [X] "Login failed" in Ubuntu. When several keyboard mappings are configured for the user, the username input uses the current mapping whereas the password input uses the default mapping, and leads to "Login failed" errors.


 * [X] In the login fields,  or + does NOT let the user navigate between the "Username" and "Password" fields.


 * In Multiplayer, a player can see 2 players, one is moving and one is not moving. This can happen when a player teleports to somebody suddenly. It creates lots of lag, and then you will see another player from where the player teleported.


 * If you tab out without having a GUI open (Esc/Inv) it will act as if shift is held down when clicking on items.


 * You aren't able to place a Jack 'o' lantern or a pumpkin on a fence.


 * When having your aim on a transparent block and looking up at the clouds, the clouds go through the line.


 * When Fishing with field of view (FOV) slider different than the default the fishing line graphically becomes disconnected from the rod.


 * Minecraft sometimes cannot be closed, especially after the Out of Memory screen shows up. [!]


 * When walking in a certain spot in Minecraft it may crash. The only way to fix this bug, is having a back-up of your world, otherwise your world will become unplayable forever. [!!]


 * Since 1.8 on Linux, the mouse gets blocked on window borders in fullscreen mode, so you can’t turn around freely. Radeon+KDE, fglrx+Unity and Nvidia+Gnome exhibit this behavior. Workaround : press Esc to bring up the menu and Esc again to dismiss it.


 * If you're flying in Creative mode, then save and close, then reload the world, you stop flying.


 * Occasionally, when you start up Minecraft in Windows, an error screen will appear which says: "Could not find the main class: net.minecraft.LauncherFrame. Program will exit.". Sometimes this will occur more times in a row, but mostly after 2 attempts Minecraft is started.


 * When playing Minecraft for a long time (like 1 hour), trying to expand the Minecraft window can cause to freeze Minecraft for a while and sometimes crashes.


 * While sprinting if you hold the jump button and repeatedly hit the ceiling you will move at about twice the speed of normal sprinting.


 * The main menu lacks a quit button in the stand-alone version. The only way to end the game is to, if using full screen mode, drop out of full screen mode and use the close button on the window.


 * When minecraft is at the main menu an you open task manager and any other program that it priority is in front of all windows, the window will be the moving pic on the main menuit will also increase fps.


 * [X] You can't hold down the left mouse button to continuously attack anymore.


 * [X] You can't hold down the left mouse button to to break a minecart anymore.

Graphical

 * On some graphics cards, the renderer will often fail to render complete darkness, creating a flickering effect when one looks down a long dark cave underground. In the frames when complete black fails to render, you can see past the walls to other cave systems and underground features. This seems to especially happen when the player's height is under 64.


 * Graphic cards affected by this: Mac Intel GMA 950 (known for minecraft issues), nVidia GeForce GTX 470, nVidia GeForce GTX 560 Ti, nVidia GeForce GTX 570, nVidia GeForce GTX 580, Nvidia GeForce GTX 260, nVidia 8600 GT, AMD 6770 (2011 iMac Revision Only), GeForce 8600GT, ATI Radeon HD 4600 Series [Add yours!]


 * When sailing across an ocean, the water horizon is a bit higher than the actual horizon and flickers constantly, as if the horizon was z-fighting with the sky dome.


 * FPS on Intel graphics cards can be doubled or tripled with debug (f3) on. This is especially noticeable when using HD texture packs.


 * As of the new lighting engine in 1.8, glowstone blocks placed directly behind or under glass do not appear brightly lit. This is caused by the glass casting a shadow on the glowstone.

Audio

 * The OpenAL32.dll and OpenAL64.dll that come with Minecraft do not work properly. This sometimes causes Minecraft to crash when players turn sound on in the options menu. On Windows machines, deleting Minecraft's OpenAL files usually solves the problem, because Minecraft will then automatically use Windows operating system's copy of the OpenAL DLL, which works properly.


 * The audio position of the player and mobs lag behind where they actually are. This is most noticeable when an animal makes a longer sound at the same time as it moves (e.g. a cow mooing). The mob continues walking, but the sound keeps coming from the tile it was on when the sound started. The supplied OpenAL DLLs lack 3D audio so it's hard to notice. However if you replace these DLLs with alternatives (such as the ones provided by the Creative drivers) you can notice that when you walk the footstep sounds are generated from where you were coming from, rather than directly underneath you.


 * Saves might become corrupted when a Jukebox is activated with a Music Disc.


 * OpenAL64 does not work with 64-bit Java. This causes Minecraft to crash if sound is turned on.  The solution is to download and replace the OpenAL64.dll/lib from LWJGL package.


 * Rarely, when Minecraft starts up, there is no audio at all. Restarting the game fixes this. It is possible that this is caused by moving the window or switching windows while the game is loading (after you hit the login button). To prevent this from happening make sure you maximize the window before you hit login, and watch it load up.


 * When a waterfall is flowing nearby and it is raining, the sound of rain cannot be heard.

Terrain Generation

 * Flowers and tall grass can be generated on dirt blocks underground when it is bright enough.


 * A similar bug as the "same chunk rotation bug" that has been solved exists for biome terrain top layer block replacement algorithms. The chunks are not rotated, but the sand pattern and biome-based layer thickness values are calculated with mixed Y and Z coordinates, causing visible and invisible artifacts. Source code for fix has been made available.


 * Large sections of "floating blocks" have been generated on new worlds for some clients from a world in 1.5_01. The error only seems to appear in coastal areas in a large scale, floating blocks include: dirt, leaves and logs so far with select ores. Snow blocks seem also to appear on water. Floating sections of dirt are commonly found in mountain biomes


 * As a result of creating lakes late in terrain generation, floating trees, sugarcane, cactus, and snow can occasionally be found floating above a lake.


 * Water and Lava lakes can be generated inside frozen oceans. Example.


 * There may be a hole in a dungeons floor, because a lava/water chamber or mineshaft may generate in the same place. If the hole will be under spawner or chest, that block will disappear.
 * Large chunks of ocean can be generated into the terrain without a smooth transition, causing large squares of ocean cut into the land. However it only seems to occur on plains.


 * Red flowers (Roses) no longer naturally occur, but can still be obtained by using bonemeal.


 * Occasionally, cubic pockets of air can be found underwater. These can form inside rock faces, on the ocean floor, or even in the middle of the water.


 * Mushrooms can spawn on leaves of trees.


 * In some cases, when deleting a map save and immediately making a new one with the same name without closing Minecraft, the new map created will be the same seed as the seed before it with all chunks loaded exactly the same way as when it was deleted. Untested for Survival->Creative and vice-versa.


 * As of 1.8 if you go outside of generation of a 1.7 world an endless ocean generates over regular 1.8 land and you may see underwater trees occasionally. Also happens to new worlds created in 1.8.

"Placed stronghold in INVALID biome at (53, 34)  Invalid memory access of location 0x8 rip=0x101113a42   Segmentation fault   logout"
 * Terrain generated on a multiplayer server will attempt to place strongholds where it is invalid, this results in a crash of the server client. It will create something similar to this in the terminal window.


 * [!!] If you generate a map in Beta 1.3 and generate new chunks for 1.8 (by moving across the Nether), attempting to enter the terrain generated in 1.3 will cause the game the crash.


 * Snow layer blocks can be formed on tall grass but as tall grass dissapears when there is a block on top of it there will be random floating snow layer blocks in snowy biomes. these can be used for traps or secret entrances to bases.

Lighting

 * 1.8's new lighting engine makes Minecraft unplayable on some computers. The game will load just fine, and the menu will be visible, but if a save file or multiplayer world is opened the game will blackscreen.
 * [Known computers that the bug takes affections are Macs running an OS older than 10.6]


 * With the introduction of 1.8, some transparent blocks on XP and Windows 7 machines, along with all the mobs will flash rapidly and can cause seizures in players looking at them.


 * Affected blocks include:
 * Signs
 * Chests
 * Glass (in some instances)
 * All passive and hostile mobs.
 * The players hand model (in very rare instances)


 * If you put any block that gives off light nearby or in water and destroy it a light source will stay as if it had absorbed the light Lava turned into obsidian and torches destroyed under not-falling sand/gravel have the same problem too.


 * In the NPC villages created by 1.8, sometimes there will be torches that are emitting no light. This can be fixed by anything that updates the torch.


 * Smooth Lighting doesn't work when shadows or light is cast on water.


 * Smooth Lighting acts weird on certain blocks.


 * On some systems, nighttime can appear excessively dark.


 * Blocks placed above snow-covered grass cause the lower blocks to appear darker than they should, but only with smooth lighting.


 * The top face of a button will appear darker when smooth lighting is on. This does not matter on what other lighting or blocks are near it.


 * The side of the top half and the top of the bottom half on stairs are black on smooth-lighting where they meet.


 * Some mobs (pigs and sheep confirmed) will alternate between looking slightly darker, and normal "brightness", as they bob up and down while floating in water.


 * In 3rd person view, putting the camera in the water causes under water overlay, and vice versa.


 * Signs can be completely black when not looked at directly.


 * With smooth lighting enabled, corners of blocks visible next to brick or stone brick stair blocks appear darker than they should.


 * With smooth lighting enabled, blocks directly behind glass are dark when light should pass through the glass. This only occurs to the glass block, not the glass pane block. Smooth Lightning Comparison between the glass block and the new glass pane block


 * In darkness XP Orbs don't show any colour or "glowing" effect.


 * Certain paintings are very dark and in some instances the colours cannot be seen. Placing torches next or under the painting increases a small amount of light, placing it on the top makes the painting light as it should be.


 * As of 1.8 Glowstone no longer appears to glow under Smooth Lighting. A shadow is cast on it as with any other opaque non-glowing block.

This same lighting bug can also be noticed on redstone repeaters and the side of fence poles and stairs that are against a wall.

Stereoscopic 3D

 * Stereoscopic Minecraft has issues rendering chunks other than the one you spawned on and the ones directly around it.


 * Grass is grey after logging out in 3D. Grass will regenerate colour when a block is placed

Achievements and Statistics

 * It is not possible to get the "Sniper Duel" achievement in SMP when killing skeleton even at a distance of 60 blocks.


 * Shift clicking on furnace result wont count toward statistics.


 * Food\hunger not tracked by statistics.


 * Player kills not tracked by statistics in SMP.


 * Throwing leather on the ground earns the achievement for killing a cow, thus getting leather.


 * The "Getting Wood" achievement is obtainable under any circumstance where a block of wood is collected, rather than only from destroying a block of wood.


 * Achievements and Statistics saved when playing offline and achievements saved when logged into Minecraft.net are separate and do not sync.


 * Achievements and statistics are reset when Minecraft is shut down unexpectedly (e.g. due to a power outage).


 * "Times crafted" is bugged: Example: When holding 36 wooden planks, while clicking and crafting 4 wooden planks more, the stats believe that you have made 40 instead of just 4 new planks. Now you're holding 40 and crafts 4 more, is 44 added to the stats.

Beds

 * While sleeping, particles (torches, furnaces, etc.) do not "adjust" to face you, some of them may look flat or even be invisible.


 * Beds placed in fully enclosed areas (on both sides and with only one space above), or beds placed with no ground even with the block under the bed on either side (with only one space above), can cause you to wake up inside a wall, killing you and potentially destroying your items. This is due to player placement when you wake: if the game cannot place you on the ground level with the block below the bed on either the left or right side, it will place you on top of the bed. If there's only 1 block height above the bed, your head will become stuck in the ceiling, killing you.


 * Beds cannot be placed on snow.


 * Beds being broken appear to get brighter.


 * You can sleep while in a minecart or a boat. You still move with the minecart or boat but you may lose air when sleeping in a boat in water.


 * You can sleep during a thunderstorm, even during the day, because it is dark enough to sleep.


 * If you walk very far away from your bed and then die, you do not re-spawn at your bed and instead spawn at your original spawn point, receiving the message "Your home bed was missing or obstructed". This is probably due to the fact that the chunk has been unloaded.


 * If you break your bed while in it, you will wake up taking no damage, but making the hurt sound and when you touch walls 2 blocks high, you take damage. Also, you are able to walk through transparent blocks (e.g. Glass or Leaves) if they are only 2 blocks high. Water is treated like air aside from the fact that you can still drown and it breaks your fall. This glitch remains until you sleep or die.


 * Monsters spawn in your house if you go to sleep inside a room with a double-door that leads to the outside. This is caused by the second door placed being inverted, and the game thinks the door is open. This can be fixed by having the inverted door open when going to sleep.


 * If a player tries to sleep in a bed next to one or more other beds in multiplayer, and someone is sleeping in one of the beds next to it, the player will often get the message "Bed is occupied".


 * Sleeping in a bed that is next to a ladder will make you lay down beneath the bed.


 * While sleeping in a bed you can use the /tp command to teleport yourself to another player, you will appear on the floor sleeping next to the other player and if you click the leave bed option you will return to the bed's position.


 * In creative mode, it is possible to fly while sleeping.


 * Occasionally when you've got blocks in an arch behind you and a 2 block wide painting directly behind you your head moves to the front of the bed


 * Occasionally when the blocks underneath a bed have been destroyed when you get into bed in 1st person view you appear to slide to the side or "Fall out of bed".

Minecart

 * Powered Minecarts only push minecarts going west-east and east-west (north-south and south-north tracks cause powered minecarts to clip and stall).


 * When interacting with a Minecart+Chest or Minecart+Furnace while holding a usable item (e.g. filled bucket, bow and arrow), the item will be used when the chest is opened (bucket emptied, bow fired) food no longer is used due to it taking time before eating it.


 * A player pushing multiple minecarts of any type can only push them going north-south. Attempts to push east-west only result in pushing the last minecart in the group, and sometimes no carts at all.


 * When closing or disconnecting from a server while sat in a minecart, on re-login you will be in a state of sitting but able to walk around until you sit back into the minecart you were in previously. This bug happens every time you load the game.


 * When Minecraft crashes after you have ridden a minecart, they occassionally get duplicated on the rail you rode on.


 * Moving carts do not load chunks if there is not a player in them, making long-distance transport (i.e. automatic transport of goods via storage cart) impossible, as they will stop once they hit a chunk border.


 * You can enter a minecart on the other side of a wall if you know its location and attempt to enter it from approximately 32 blocks away. Only happens in creative mode.


 * Riding a minecart over a rail generated floating in the air in an abandoned mineshaft causes the client to crash.


 * When riding a minecart at any speed with 2 block high and 1 block wide room into a corner, you may take suffocation damage.


 * Items dropped on a rail will effectively stop a minecart immediately if it's riding on that rail, no matter how much speed the minecart has.

Chest

 * Both chests can also be opened while the player is standing on top.


 * Double chests from 1.7.3 SMP worlds appear rotated to orient along the North-South line, placing a transparent block where they actually are and being able to walk through the ghosted half. The rotated half will overlap with solid blocks to the south.


 * when you place a sign and then break it and place a chest there it, will not place a chest but instead place another sign, which if you right click to use the chest it will crash your game.
 * Chests from 1.8 spin on an irregular axis when on the ground


 * As of 1.8, Chests' lighting depends on where you're standing, and how far down you look. It may look black, depends on where you looking too. possibly a glitch in how the entity is rendered vs. how it is coded. Looking at the new smaller chests still show the bounding box for a "normal" sized block. The render may be "fighting" with itself as the chest is, technically speaking, "inside" itself, and thus "must" be dark, but it's "surface" is not obstructed, and thus must be "light" This could explain how this bug affects signs and other Blocks smaller than their bounding boxes.


 * Both single and large chests will stay in the open position if rapidly opened/closed. (Only SMP)


 * Sometimes when opening chests in multiplayer the server will crash.


 * As of 1.8.1 when a chest is opened and exited out of, the lid of the chest may remain opened.


 * If you shoot an arrow on a chest, it will close immediately when you try to open it.

Doors

 * If you close a door on yourself, you can stay in that door. When jumping in it, you can stand on half a door, making it possible to reach other areas above you.


 * When opening and closing a door, the sound it makes is randomly chosen between the open and close sounds, instead of specifically using the open sound for opening the door, and the closing sound for closing.


 * You can't place doors on glass or snow tiles.


 * The routine which determines whether you are sleeping in a safe place seems to ignore actual door state (open/closed).


 * Open double doors will prevent players from walking in the space between the two doors (acting as if there was an invisible door in the middle), forcing the player to close one door or closely hug the side of the opening to cross.


 * While charging a bow, Hitting a door by left-clicking will not open it, But the sounds and door effects happen after shooting the bow.


 * Occasionally in SMP, when you attempt to place a double door, the one you place pops back out, resulting in a half door block to remain, while the actually "inventory" door block, is on the floor.


 * In SMP, doors that have been placed in the unchangeable spawn area are buggy for non-ops when they try to open and close them.


 * [X] Walking across a series of trapdoors doesn't produce any footstep sounds. Walking across the edge of the block adjacent to the trapdoors (ie, walking across the top of the trapdoor block) makes the walking on wood sound.


 * When using the default textures, the hinges on the edge of the door are shown as 3 when closed and two on the thin edge when open.

Farmland

 * Saplings can be planted on tilled soil, however they will never grow even when bone meal is used.
 * Items will not eject properly if a block is placed on them and the items are touching one side of farmland.

Fire

 * Fire on Netherrack spreads through walls, setting stone on fire.
 * When it's raining, fire can make extinguish sounds, no matter if the rain can reach the fire or not. Unknown at what distances.

Furnaces

 * When smelting any ore and viewing inside the furnace at the end of the process, the player is dropped out of the furnace menu losing all smelted items and excess fuel.

Glass Panes and Iron Bars

 * Glass panels and Iron bars don't connect to double slabs, stairs and pistons.

Ice

 * Ice blocks do not have the slide effect on their border if no other ice block connects on them. Player will not slide even if the ice block is supporting him/her (i.e., the ice block borders air). Walking around in grayed-out area will not have the slide effect.
 * You can see chunk borders in ice in Fast graphics.
 * You can't see water and lava through an ice block, and vice versa.
 * [X] Water surfaces directly under ice blocks allow you to see underwater as if there wasn't any water surface there.
 * Single blocks of ice that are melted via torch, glowstone, etc. do not flow. This is because the water/ice block does not update. Placing a block next to this water block will cause the water to flow. This will also happen if an ice block is destroyed in the immediate premises of a light source.

Interface

 * If the player rides a vehicle and then opens their inventory, the player's hands will shift position in their view. This is most noticeable when the player has a map as their active item, and persists until the player opens their inventory again, even surviving reloads of the world.
 * Pressing a jump, movement, or sneak key at exactly the same time as opening the inventory will cause the action to be held. The inventory may then be closed, and the action will continue until the according key is pressed or the inventory is opened. Multiple keys may be "toggled" in this way. This trick can also be performed by clicking workbenches, furnaces, chests or dispensers.
 * Sometimes a jump or move key will get jammed and you will keep moving until you press the key that would normally make you jump or move that direction.
 * Opening the inventory while the player is sneaking will cause you to not able to click and drag items. Anything clicked will instantly be taken to or from hotbar. Survives world reloads and client reloads. This only applies if the user's sneak key is SHIFT. To fix this bug, simply hold down SHIFT and open your inventory again. You will now be able to relocate items around in your inventory.
 * When player touches a 2 blocks high pillar in 3rd person mode, the character's shadow displays on top of the pillar.
 * In the inventory the labels of the current window will overlap the currently moved items.
 * If you open your inventory while sitting in a vehicle and wearing armour pants, you will see that your legs will be bent in a sitting position but your armour pants will not. They will remain upright and come off your body right through your legs. The reverse happens if you put on armour while in a vehicle and leave it.
 * Rarely, you can see white pieces on the border of any block. If you attempt to click on the line, nor the two blocks of the border are hit, but you hit THROUGH those. This only occurs when blocks are placed diagonally from each other. However, this bug cannot be abused because it is a rare occurrence.
 * When you sprint in water you won't go faster, but the hunger bar still depletes faster than normal.

Lava

 * Sometimes, lava won't cause damage. More common in SMP.
 * In SSP and SMP, you may take damage from lava but you are not set in fire. This occurs more if you are standing at the edges of the lava.
 * When a burnable block like wood is completely surrounded by lava, it won't be set on fire, because there is no room left to spawn the fire.

Mobs

 * If an enderman places a leaf block it wont decay no matter what its connected to
 * Arrows stuck in Ghasts and Large Slimes are monstrously large.
 * Spiders and Enderman glow bright white when underwater and underlava and when you're far away from them.
 * Wolves seem to have become very rare for some, but for others, extremely common.
 * Endermen don't become hostile if you target them. They become hostile if you target 2-3 blocks above them. They charge and attack if you stop targeting the place above them.


 * Tamed Wolves will attack you if you shoot yourself with an arrow. This can be achieved by looking straight up, shooting an arrow, and moving forward a small bit to compensate for a small amount of curve. Another way is to shoot an arrow at the ceiling and stand directly under it and destroy the block the arrow is on. This will cause the arrow to drop and hit you.
 * Wolves appear black if it's raining on them.
 * Tamed wolves hit while they're in sitting pose will start jumping towards the player who hit them, they can attack even their owner.
 * Tamed wolves will occasional start following the player though they're left in sitting command.
 * Endermen become hostile within a certain amount of blocks not looking at them.
 * Endermen will occasionally walk into water without interaction causing themselves damage.
 * Mobs may emit their idle sounds in the moment they are dying. This sounds like a second mob is nearby, but is actually not the case.
 * A wolf's muzzle slides in or out of its head depending on whether the wolf is looking left or right.
 * A cow's horns slide to the left or right of its head depending on whether it is looking left or right.
 * On SMP, if you are lagging, any monster that notices you and starts walking towards you, will not look directly at you right away.
 * Rarely, a hostile mob stops being hostile. Also, they'll stop moving, only looking around, and can drown easily while standing in water. But when you hurt them, they will become hostile again.
 * Every mob seems to jump the whole time against a fence. This is probably happening because the mobs see this as a normal block, so attempting to jump on it the whole time.
 * Some mobs can occasionally spawn inside or on top of trees
 * Especially in SMP, all mobs clip against water flows or small openings. This can cause them to get stuck. They then appear to warp up and down 1-4 blocks constantly, and can be hard to hit due to the dancing hitbox - however they can still attack you. Slimes are indestructible when this occurs, due to their natural jumping motion breaking through the players' swing, causing mining of the block it is stuck in to reset but not damaging the Slime.
 * In some cases spawning in well lit, flat grass area mobs spawn out of control making game extremely slow or non-responsive(with some correlation of the chuck relocation error)
 * Passive mobs, usually cows, spawn underneath trees and fail to take damage or get pushed to an open spot. Related to water clip bug.
 * Sometimes, in SMP, Endermen don't attack even if you look at them, they will only attack you if you attack them.
 * Even when server is set to hostile mobs spawning = false i.e. peaceful, spawners in abandoned mines still spawn cave spiders.
 * Sometimes you can hit a mob when there is a block between you and him.
 * Sometimes this above also occurs with non-transparent blocks.
 * If a player dies while poisoned from a cave spider, they will continue to take poison damage upon respawning. (Confirmed in SMP, unconfirmed in SSP)

Paintings

 * Paintings never use smooth lighting.
 * Light goes through paintings.
 * You can place paintings in signs and torches.
 * As of 1.8, paintings with a block directly above them will appear totally dark, regardless of how much light is available.
 * Paintings appear black if they're in light level lower than 8.
 * If a painting is destroyed while sprinting, 2 painting blocks will be dropped instead of one.
 * Placing a painting on a block with a torch on it in SMP will make it be dark. The only way to destroy it then is to destroy the block where the painting is placed on from above.

Pistons

 * Pistons are not recognized as a redstone device, therefore redstone will not curve into them. Redstone placed underneath pistons will also not power the device. Instead redstone has to run straight into the piston.
 * Walking straight on to horizontal piston from head to container with a hole under container causes you to fall into the hole.
 * If a piston is extended, the player can walk right through the back/fall through the top.
 * Sticky pistons may not pull back the block when they are toggled on and off rapidly.
 * If a piston pushes a block that is on fire, the fire will be put out.
 * When one sticky piston is connected to another, the one that is connected will not pull a block the is attached to it.
 * When a cake is placed on a piston, it will disappear when the piston is toggled on.
 * When a redstone torch is placed right under the piston if you remove the block where the redstone torch is placed while pressing w(forward), it will make you fall into that hole and you'll be trapped and in 3rd person view making the piston invisible for you at that point.
 * When you try to activate a piston placed underwater while pressing w(forward), you'll be able to go through the piston.
 * Placing a redstone dust on a block diagonally back and up, and powering it, from a piston will power the piston, in some cases causing the piston to get stuck extended. This only occurs if there is no block directly above the piston.
 * There is a duplication bug with sand and gravel, when sticky pistons are aimed up and distract and retract at high speed.
 * There is a bug with pistons stacked on top of each other; Two pistons set to extend in sequence work fine, as it does with one block on it, however with two or more the bottom sticky piston will not extend, and when retracted it leaves a space between the two pistons (as if the bottom piston had extended but did not pull the other one back down) and with gravel/sand the blocks actually switch places.

Portals

 * After entering a portal the distortion animation can appear even if the player hasn't moved but this will not teleport the player back.
 * In SMP, going through a portal while on fire will stop the fire animation when the player arrives at their destination, though the player is still on fire and will keep losing health.
 * Riding a Minecart/Boat/Pig into a portal causes you to get stuck in a block.
 * Riding water into a portal while in the crafting table interface will duplicate the items and sometimes become infinite.

Redstone

 * The display of redstone wire differs from its behavior when it's placed beside a block with torch on top. Namely, the wire turns, connecting to the block, but doesn't actually power it.
 * In a straight line (any variant works, just straight is easiest to describe), place, from left to right, Redstone torch, block, redstone wire, block, then any powered device, including repeater, piston, door, and powered rail. Then, destroy the wire in the middle, and the second block and the powered device will remain powered. Destroying the second block stops power going to the device.
 * Dispensers, pistons and powered rail can be powered 1 block higher also (like a door), if it's a powered block that's powering the pistons (either 2 blocks above the piston or 1 block up and 1 block to the side), the piston won't update properly. The next block update will cause it to react.
 * Consider a wire that powers a block, which then powers a repeater. When the wire next to the block is removed, the repeater will remain powered until the next block update.
 * When a wire is powered, and another source of power is connected to the wire, the wire power won't be recalculated, blocking the new signal.
 * N/S repeater; old two-torch repeater that propagates in 1 tick, opposed to 2 ticks.
 * Glass and ice behave like a solid block when blocking off wire, but they let the current through, like their old behavior.

Repeater

 * Doors, trapdoors, TNT or dispensers beside blocks powered by repeaters are not updated when the repeater changes state (forcing an update by placing a block updates the door).
 * Arrows momentarily detach each time a repeater changes state.
 * Walking over a repeater or trapdoor in a 2 block high space can cause the player to fall in the block below, allowing him/her to walk around in the block. The player can jump out the block at any time. You can also fall in the room below if its ceiling is 1 block thick. Video demonstrating the bug.
 * A repeater transforms short pulses if the pulse is shorter than the repeater's delay.
 * Repeaters behave badly with negative short pulses.
 * When a repeater is placed west of power (powered block, torch, lever, ...), the repeater will be powered for 1 tick.
 * You can walk on a repeater from any direction, except the output side, this all if the room is 2 blocks high
 * (May be related to the above glitch) If there is only a two block space above a repeater and you are walking onto the repeater from a greater than 2 block space, you are stopped as if the repeater constituted a whole, solid, block and have to enter the 2 block space from a place without a repeater on the ground. If you're already in the two block space with the repeater, you may walk over it without a problem.

Rails

 * Powered rail fails to return to the unpowered state if a nearby block above it is powered, as seen here.
 * North/South oriented powered rails act as curved corner rails if it is powered and there is a track heading east from it.
 * Detector Rails with minecarts already on top fail to ignite redstone when pushed over the redstone by a piston.

Score

 * When the player dies, their score is displayed as "&e0". This happens because a scoring system is yet to be setup in Minecraft and "&e" is supposed to be the colour of the score number.

Seeds

 * In certain afflicted areas, placing seeds on two adjacent tilled dirt blocks will cause them to disappear, and drop a resource approximately the same percentage of the time if you had destroyed the freshly planted seeds with your hands. If you place one seed with no adjacent seeds on the afflicted area, it will disappear after a while.
 * Sometimes, seeds will stay on the dirt even after the tilled dirt reverts back into dirt by stepping, or dryness.
 * Pumpkin seeds are unobtainable from a mineshaft as of 1.8.1
 * Pumpkin and Melon plants float 1/16 of a block above farmland blocks, leaving a noticeable gap in between the two.

Signs

 * In creative & survival if you place a sign in front of another sign it will create a floating sign in its wall "phase" instead of not placing anything.
 * (Tested in multi but not single...) If you attempt to enter text onto a sign in a chunk with a fast redstone clock nearby in it, the text will be deleted as you type it out.

Slabs

 * Wooden slabs use the same properties as stone. As in producing stone SFX and requires a pickaxe to mine and doesn't get burned by Lava or Flint and Steel.
 * Grass doesn't die under slabs.
 * If a slab is placed on ice, it still has the "slippery" effect.
 * If you build a tower of slabs from the top down so there is half a block between them, placing a slab on top will create a double slab at the lowest slab, destroying all other slabs in the tower.
 * You can't place a trap-door on the side of a slab
 * Full blocks made out of two slabs don't behave like a full block

Stairs

 * When destroying Stone Brick Stairs you receive Random Stone Bricks block. Type depends on stair direction, 0/west - Cracked Stone Brick, 1/north - Mossy Stone Brick, 2/east - like normal(but not stackable with normal one), 3/south - normal(craftable).


 * Stone brick stair lighting bug when smooth lighting is disabled.


 * Stone Brick Stairs have a lighting glitch where the 1/4 wall visible adjacent to the stair will be dark regardless of lighting.

Torches

 * The smoke particles from a torch can move up through solid blocks, making them visible above those blocks.
 * Can be placed on furnaces, crafting boxes, and chests when there is a glass floor or a fence in front of them, and the torch is placed on the glass. Alternatively, this can be achieved by placing a torch on another torch as demonstrated in this video.
 * Torches placed under water will break, but the area will stay lighted.
 * As of 1.8, sometimes in mine shafts, torches will generate floating in mid-air.
 * Some torches generated in Strongholds will be sideways to a wall.

Water

 * Water currents do not push minecarts or activated TNT entities around.
 * Items which are detached by water (such as flowers, wheat, mushrooms, torches, redstone torches, redstone dust, and rails) will disappear and not drop a resource if water flows onto them directly downward.
 * It is possible to place water using a bucket in the space occupied by a detachable block or a ladder (but not a sign or slab) and the water will replace it without dropping a resource.
 * Water, seen through falling water, is invisible.
 * When you swim underwater and you are looking at a nether portal, you can see the obsidian but you can't see the portal block itself
 * Water may flow upward, e.g. if low level water is diagonally connected with two water sources.

Mac OS X

 * Some Mac users have been reporting Minecraft crashing constantly. Setting the render distance to Tiny helps stop the crashing.
 * Some Mac users cannot take a screenshot when the window is maximized.
 * Clicking the "Open Texture Pack Folder" button does nothing but play a click. (Solution: Go to Finder>Library>Application Support>minecraft>texturepacks.)
 * When closing the Minecraft window it can cause the computer to crash. This can be avoided be 'Force Quitting' Minecraft by using the keyboard shortcut: cmd, alt, esc or by clicking the apple logo then selecting the 'Force Quit' option. Also you can sometimes bring up the Force Quit menu while it is frozen. Force Quitting then will solve the problem without a hard restart.
 * Attempting to use the Command-Q keyboard shortcut to quit the game does not work. The game does not respond in any way.
 * Logging in on the second monitor while using two (non mirrored) makes the game crash when you open your inventory. Logging in on the first monitor, loading a save and then moving the window to the second monitor seems to fix this. (Bug experienced and reproduced on a MacBook Pro 2011 13-inch connected to a monitor through Mini Display Port to VGA and DVI.)
 * After attempting to load a world (new or old) on Mac OS X 10.4.11 (almost always) causes a black screen. An error message to flashes for about a third of a second, which is enough time to see it but not enough time to read it. Also, connecting to a server causes a crash, making the game unplayable to all OS X 10.4.X users. This has also been reported on newer versions of Mac OS X.
 * Opening the Launcher can cause the Username field to become garbled. Tested on OS X Lion.

Skins

 * If a player wears a helmet while his skin has a head accessory portion and he sneaks, the portion appears outside the helmet.

TNT

 * TNT is transparent. This bug was introduced between beta 1.5_01 and beta 1.6.4, and is present in beta 1.8.1.

Linux
Sound may be broken because OpenAL (shipped with Minecraft) is not compiled with PulseAudio support. If this is the case then replace libopenal.so (which is located in ${HOME}/.minecraft/bin/natives) with the libopenal.so which is shipped with your OS (located in /usr/lib/).

If you are running a 64-bit system then you must replace libopenal.so from ${HOME}/.minecraft/bin/natives with the one located in /usr/lib32/. You must also replace libopenal64.so with the one from /usr/lib/.

Long story short, you must type the following the terminal/console:

"uname -m"

If you are running x86 (32-bit) then do the following:

"cp /usr/lib/libopenal.so ${HOME}/.minecraft/bin/natives"

If you are running 64-bit (x86_64 or x64) do the following:

"cp /usr/lib/libopenal.so ${HOME}/.minecraft/bin/natives/libopenal64.so" "cp /usr/lib32/libopenal.so ${HOME}/.minecraft/bin/natives/libopenal.so"

Now restart Minecraft and sound should be working properly. You may have to repeat this process every Minecraft update.

This section may be on the wrong article, if so do not remove it unless you move it to a different article.

General

 * If you click fast enough, it is possible to consume the entire durability of a tool when striking a mob. It is possible to recreate this by making a script that rapidly clicks the left mouse button and striking at a mob.
 * Advanced OpenGL will sometimes clip visible areas, especially if you rapidly turn your mouse.
 * Sometimes blocks will fail to render, creating massive holes on the ground and walls, allowing the player to see caves and dungeons under the map.
 * Minecraft loses its mouse focus on every click to X Window for a very short time or by maximizing/minimizing the window. If a pressed key is released at this moment Minecraft won't register. This will cause the player to move even if the movement key isn't pressed anymore. This is due to a bug in LWJGL that was fixed in LWJGL 2.6. Replace Minecraft's copy with a newer version of LWJGL to fix this issue.
 * Sometimes mobs within a certain area will stop moving, and entering the area will cause the player to become rooted to the spot and often vibrate wildly. Many animations, such as digging and health recovery will be broken, and mobs that the player hits will constantly loop the damage animation without dying. It is not possible to catch fire. This is often called a 'bad chunk'. Even if the chunk is deleted and generated again the bug will persist.
 * Selection bounding box breaks ATI cards' anti-aliasing.
 * There's a file called map.txt in the achievement folder inside minecraft.jar that causes performance issues. Removing it may greatly increase your performance, but may reset your achievements.
 * Unable to take a screenshot in full screen mode on some computers.
 * Occasionally a block mined will not produce a resource block. This seems to be caused by putting the reticle too close to the junction of two blocks, causing the target to switch to the block not being mined. The block is destroyed, but the resource is not dropped.
 * When a block is mined, it will produce a resource block, but will not appear to be mined. This bug normally occurs when much of Minecraft's memory is being used up and can be fixed by restarting the game.
 * If a player drops an item, saves the game and returns, picks up the item, and closes the game without saving, the item will appear both in the player's inventory and on the ground, duplicating it.

Beds

 * The player has the ability to destroy their own bed whilst in it during the fade, and as of 1.7 this allows them to take damage from walking into a wall, as the player's block collision is still disabled. In addition, when traveling on water, you would walk as you normally would on land.
 * If the block on the pillow end of the bed is broken, the player will miss the bed and sleep on the floor when the player right-clicks on the bed.
 * Equipping a sword and holding the use button while sleeping causes some glitches, like being able to see through blocks.

Boats

 * If you manage to stand on your boat while it is under water, the boat will be unable to rise. The boat will still retain horizontal movement, though, and will often slide out from underneath you.
 * If you save and reload while in a boat, you will no longer be in the boat upon reload.
 * Exiting a boat will sometimes cause the player to fall through it. This could be fixed by implementing code that would place the player one block higher than the boat when it's exited.
 * If an occupied boat crashes into an unoccupied one, only the occupied one breaks.
 * Parking a Boat on a half step port/dock (or bumping into Soul Sand) while riding can cause damage/death to player. Extending a piston upward beneath a boat can have the same effect.
 * As of 1.6.6 you may crash a boat as hard as possible into land without it breaking while occupied, but as you exit the boat after a crash if the boat taps a solid block the boat will break.

Furnaces

 * When you put coal and a smelting item in a furnace, then leave and re-enter the world, the fire icon glitches and will not shrink until the fuel source is about to run out.
 * The fire animation may not disappear even after the fuel is consumed.
 * After a use of a furnace, if there is unused fuel material inside the furnace, it will be invisible and burning animation is still played.

Glass

 * You can't suffocate while stuck in glass.
 * If a glass wall is placed next to TNT in water and you stand on the other side of the glass, you will always take only a half heart of damage.
 * Glass does not affect the orientation of chests and furnaces.
 * If Glass Pane placed near Leaves, it attaches to them.
 * If Mob stands close to Glass Pane, player can hit Mob from the other side using Bow.
 * Glass panes do not properly line up with / attach to double slabs like they do other solid blocks.

Grass

 * It appears that in arctic biomes, next to ice, and in desert biomes grass can be generated underwater by the terrain generator.
 * Grass does not disappear if a transparent block (stairs, slabs or glass) is placed on top of the grass.
 * The sides of grass blocks do not match the colour of the top side in some biomes.

Gravel and Sand

 * Gravel or sand will not fall down if it is placed above a non-solid block, like a torch or flower. If blocks of gravel or sand fall onto a non-solid block, they will accumulate into resources.
 * If you break a block below gravel or sand and are walking into gravel or sand, you will literally walk into the gravel or sand.
 * If you place a sand or gravel block then quit the game before it starts falling, upon reload, it will float. If a nearby block updates, it will fall.
 * In the Far Lands, sand and (mainly) gravel will fall in a weird way, and when they land on a block, they will (in some way) break and make pickup-entities, but still be there as a block. This is the main course of the massive lag, experienced in the Far Lands. However, it's unknown when the sand/gravel glitch actually happens, because it's first in the Far Lands, that such huge amounts of them spawns with air beneath them, allowing them to fall.

GUI

 * The debug menu may not be displayed properly when the GUI size is set to Auto.
 * Holding down or spamming right mouse button while holding down left mouse button will cause the "item action animation" to pause/stutter. The user is still able to mine, cut, etc. while the animation has paused.
 * When clicking the Back to game button, the click may "pass through" into the game, causing the player to unintentionally execute the left mouse button action.
 * In the window to add a server, all text gets reset when the widow is resized.

Ladder

 * Under certain conditions, if you are looking at a ladder, the selected block will toggle back and forth between the ladder.
 * If you press shift to pause on a ladder, you cannot select another ladder segment nearby, only the block underneath. This makes it impossible to remove ladder pieces while clinging to a ladder, unless you break the block underneath the desired ladder segment.

Lava

 * Lava can sometimes fail to generate proper lighting into the surrounding area, and will not damage the player. These pools can be traversed one layer without injury - submerging into the lava will cause the player to take damage, as well as force relighting of the pit.
 * Submerging into lava will make spiders and endermen glow bright red, tested in creative mode.
 * If a ladder is placed in a hole below lava (in any area where lava will flow) the lava will not flow onto, or destroy the ladder

Maps

 * Sometimes while viewing a map the game will switch to a "saving chunks screen" then end on a black screen.
 * At times, the player's marker will spontaneously disappear.
 * Crafting a map underground and using it sometimes makes Minecraft crash.
 * If you take out a map while The Void is visible, Minecraft will crash.
 * Some maps in SMP will display normally while exploring, but once the user re-joins vertical lines appear in the map that will not go away.
 * Sometimes maps will appear with the incorrect number on them, which can be fixed by dropping the map and picking it up again (sometimes more drops than just once).
 * Apparently right when you load a world - if you turn to the left you will encounter a 'deadspace' where your facing will stop as you continue turning past facing west (map-south). This will cause your facing arrow to 'lag' a few degrees resulting in an incorrect direction by one GUI 'tick'.  This 'deadspace' appears to save it's spot.  IE if you make 20 complete rotations to the left you can fix the GUI arrow by turning 360° 21 times to the right.  And likewise if you make 50 complete right turns, you will not encounter this bug unless you make 51 complete rotations to the left.
 * On SMP servers with a view distance other than 10, the map does not fill itself properly, and as you walk previously explored areas will get deleted from the map.
 * If you create multiple maps with shift+click you get the same map multiple times (the resulting maps are "synchronized"). You can also see other players on that map
 * As for update 1.8.1 sometimes newly created maps, at different locations will keep loading map_0
 * Maps are sometimes generated with each chuck having a different biome, such as half a mountain in the middle of a desert, or extremely flat edges of hills when they are generated next to ocean biomes. Lakes and rivers are may also be generated in perfect rectangles.

Minecarts

 * If a minecart is partially off of a sloped Powered Rail, in such a way that it does not move, and the player enters and leaves the cart, they may fall through the block beneath it.
 * In multiplayer (possibly single player too) if a minecart travels a long circle (outside a player's render distance and back again) occasionally the minecart will become invisible and cannot be interacted with, but it will still interact with the world (activate detector rails etc.) All nearby invisible minecarts will become normal again after disconnecting and re-joining to the server.
 * Minecarts can go off tracks or crash through the ground if their momentum is too high.
 * If you start sneaking right after destroying a minecart, you may crash and get buried, but there is also a chance you will get multiple minecart drops.
 * When exiting Minecarts when there is a block in front, the user may rarely fall into the block beneath the cart.
 * If TNT is detonated near a minecart, it occasionally drops more than 1 minecart.
 * A player/mob can be in a burning minecart without taking damage or being set on fire themselves.
 * Water does not put out burning minecarts.
 * Minecarts will interact with blocks next to the track while turning. When a track turns to North or South and there is a block next to the turn track, a minecart will stop rather than make the turn. This does not seem to happen on turns going to East or West.
 * When a minecart goes around a U-turn at extreme speeds, the player's viewing angle may not spin around, and will rather stay facing forward.
 * If the player saves in a minecart, they will be ejected from it and multiple copies of it will appear, possibly getting stuck right next to each other so that they accelerate at high speeds. If this happens to minecarts with chests, the items inside the chests will be duplicated as well.
 * Riding a Minecart into a Nether portal will no longer crash the game, but will trap the player in the portal block. The player cannot exit the Minecart.
 * If you save and exit while riding a minecart then load the game, you will fall through the block below you and placed to the nearest open area, this may cause to lose hearts.
 * Getting in (untested getting out) of a minecart will cause the user to eat food (only tested with mushroom stew, not tested on multiplayer)
 * As of 1.8 a powered minecart will not push another cart up a slope.
 * As of 1.6 a powered minecart will not push another cart east-west.

Mobs

 * Sometimes, if a creeper explodes next to you, but you don't die (you could barely be alive), your inventory items are duplicated by two.
 * If a mob is riding a minecart and 2 or more mine carts get stuck in each other, after destroying or moving the carts away from the other carts the mobs will be invisible.
 * When up close to any mob or player in the Nether, the inventory GUI will become much brighter.
 * Ghasts will shoot at the camera, not the player entity. This frequently causes fireballs to miss you in 1st person. The deviation is even larger in 3rd person view. This bug does not occur in multiplayer.
 * Mobs can move briefly before map data is loaded when signing out and loading the world, usually resulting in the mobs getting stuck.
 * If a wolf is tamed when it's attacking another mob, it may still attack it when on sitting animation
 * If you hit a pig with a saddle (by left-clicking) it will deal normal damage but it will also place the saddle on the pig.
 * If a creeper attempts to reach the character by running into a corner, and the block it is on is a ledge with no blocks on its level (or possibly above it), the creeper may stop as though it is hiding, then never move from that spot again unless the player breaks a block or moves the creeper to change these conditions. If the character moves to the other side, the creeper will randomly snap between staring at the player without moving and looking around as though it doesn't see the player. If the player gets close enough it will still explode.
 * If a block is placed directly above the water, and a wolf swims against it, it gets stuck and drowns unless the block is removed.
 * Tamed wolves or any other mob, whether friendly, neutral or hostile, will not avoid harmful blocks, such as cacti, fire, or lava.
 * When walking in a straight path for about 1500 blocks, the amount of spawned mobs will start to stack up, not de-spawning. By the time the 1500 block distance is traveled, over 170 mobs will be spawned behind the player. This causes the area the player is in to stop spawning mobs entirely. (Confirmed in the Nether, unconfirmed in the Overworld.)
 * If you save and quit directly after killing a mob, upon rejoining, the mob is still functions like it is alive, yet it's body is red.

Mushroom

 * Mushrooms can live and grow under direct sunlight under glass.
 * If you place any block next to a mushroom, all mushrooms and other plants will be destroyed.

Nether

 * The lighting in the Nether can flicker in the distance as if in a thunderstorm if there is one raging in the over-world.
 * In the Nether corner Far Lands, About 3200000 X&Z, There will be a place where there is light, but no lava. (This is a part of the whole Far Lands "bug")
 * It is possible (although very unlikely) to have your main spawn point in the Nether the first time you go to a world. This means you can't get out of it without cheating because there is no water to make obsidian for portals, or iron to make Flint And Steel.
 * Small patches of blocks are a darker hue than other blocks, this reverts to normal lighting when a block is placed or removed from the affected area.
 * When a Ghast is near and attacks you, the entire game is muted until the game is logged off and exited. Possibly the cries or the attack sound of the Ghast.
 * All portals created in the over-world will point to the same portal in the Nether no matter where the over-world portals were created. After the first portal is created in the over-world, all subsequent portals must be created in the Nether in order for the portals to work properly.  If an additional portal is created in the over-world, it has a chance of rerouting all Nether portals to exit from the new portal.
 * When leaving a Nether portal, pressure pads don't work unless you break and replace.

Paintings

 * Paintings can be placed inside snow.
 * If a painting is placed on a block with a fence on top, the painting may be 1x2 in size. This can not be removed without breaking the block or fence.
 * Since 1.8 - paintings turn black if there is a block above.
 * Paintings go through step blocks.

Pistons

 * When a piston pushes a block of sand towards a space with redstone dust on it, the game will crash and keeps saying saving chunks. This bug is nearly the same as the bug that has just been fixed where pistons couldn't push towards a space with redstone dust on it.
 * If 2 sticky pistons are placed on each other the bottom piston won't pull the top piston back down if the top one is still active.
 * If 2 sticky pistons are placed on each other with the top piston active and the redstone power (going) down, the bottom piston won't pull it's self in even if it's not a sticky piston.
 * If 2 sticky pistons are placed on each other with the top piston active and the redstone power on, the bottom piston won't activate at all.
 * If a sticky piston pushes a block of ice while in water, the arm of the piston will become invisible. video example
 * If you attempt to use a piston on a water source, the game will crash and keeps saying saving chunks.
 * Sticky pistons are only sticky while retracting. They lose their stickiness once fully retracted, thus a sticky piston pointing downwards can pull a sand or gravel block upwards, but the block will fall back down once the piston has fully retracted. This also means that a column of upwards-facing, extended sticky pistons that are deactivated in a top-to-bottom sequence will not result in a shorter column of retracted sticky pistons, but in a series of retracted sticky pistons every other block along the height of the column.
 * A player standing on top of a downward-facing, extended piston will fall through it when the piston is retracted.
 * Pistons powered from above can become stuck. See here.
 * If a piece of rail on a block with a button over a sticky piston and the button is pressed: the rail is pushed upward, the button is destroyed and the rail stays floating in midair over the block it was previously on.
 * If you have 4 pistons simultaneously pushing a boat or a boat with a person in it upwards, the boat (along with the player in it) will rise up normally. but if the person is standing on the boat instead of sitting in it as the pistons push upwards, the boat will stay where it is (inside the extended pistons) while the person will be pushed up. The boat will return to normal once the pistons are retracted. this bug applies with or without water.
 * Pistons can be powered from two spaces above. A powered block above an air block, which is above the piston will cause the piston to extend.
 * Pushing a Jack-O-Lantern or a pumpkin with a sticky or a normal piston will destroy the Jack-O-Lantern or the pumpkin
 * Pushing a boat upwards with two pistons can occasionally cause you to die instantly, suffocating.
 * Using a sticky piston to push a normal piston downwards on top of sugarcane will cause the normal piston to be destroyed, without dropping (it simply disappears)
 * If you have four pistons in a plus shape facing inwards and a lever in each corner, if you stand in the middle and you activate all of them, then deactivate the lever next to the piston that is not extending then the one that is extending, if you get the combination of levers right, you will see that the piston at the front of the extended piston will disappear and the piston next to the one that extended will lose its arm.(works with sticky pistons, have not tried with normal pistons)

Portals

 * If the game is closed while entering The Nether, you will be sent to your spawn point on earth without held items, as if you were killed. However, it ignores the player's spawn point made by sleeping in a bed.
 * If a player opens a work bench and putting items in it, while going into the portal(with water or something like this), the items falling down and they are very buggy, but the most time it's able to multiple them, all stackable items are 1x doubled, non-stackable endless times. Video demonstrating the bug.
 * Creating a portal in the nether has a high chance of linking permanently to a pre-existing portal in the overworld. This makes the new nether portal a one-way link.

Pressure Plates

 * All pressure plates have a tendency to fade to black when smooth lighting is on in some situations.

Rails

 * If a powered rail is placed directly adjacent to a slope and the power source is a lever hidden in a hole in the wall, riding over that rail will cause both the minecart and the player to be teleported into the hole in the wall, causing suffocation damage or death.
 * If a rail is powered by a button that is directly above the rail and there is redstone wire leading from the block right behind the button, pressing the button causes the rail to be powered until the rail is destroyed or redstone is connected to the rail.
 * When attempting to have 2 rows of detector/powered rails running along side of each other facing east/west they are corrected to face north/south, making it impossible to have 2 rows of detector/powered rails running along side of each other facing east/west.

Rain

 * In SMP (And SSP, maybe?) Rain can go through wood or glass.


 * In SMP, when logging in to a server that's raining, rain will leak through blocks arbitrarily, pretending that they are not even there. This can be fixed by updating or right clicking the block or the block next to it, which will stop the rain in that one block.

Redstone Repeaters

 * Redstone Repeaters don't always toggle correctly; when a circuit is switched on, some repeaters stay off and vice versa.
 * Can happen multiple times over the same circuit.
 * More likely to happen over longer distances.
 * Removing the Repeater and then replacing it will put it into the proper state, but the problem can come back at any time.
 * Occasionally, when walking off of a redstone repeater in a room with a ceiling height of 2, you fall through the floor into the block down and next to the repeater.

Redstone

 * While destroying a block, quickly applying redstone repeatedly will cause you to see textures of different blocks. Also, quickly removing redstone AND attempting to mine the block it is on has a small chance to make it show the glitched grass texture on top of the block. More chance of this occurring on a dirt tile. This glitch is more common in SMP but can happen on SSP when encountering frame rates of less than 25.
 * There is a bug where redstone can be turned into obsidian using this device. Tested in SMP v1.7.3.

Redstone Torches

 * Sometimes they don't return to on state until, server restart can fix it.
 * The 80 scheduled random block updates are responsible for messing up synchronized circuits.

Sapling

 * A tree can grow into Iron Bars, slabs and in some certain other blocks, deleting them.
 * Birch and pine saplings will not grow adjacent to walls or other obstacles, like normal saplings will.
 * If a player is 2 blocks away from the sapling and uses bonemeal on it, the player will get stuck in the leaf blocks, able to move and not get hurt, like the leaf blocks are not even there. This only applies if the player is using Fancy graphics.

Slabs

 * Skeletons and Zombies will not be set on fire in direct sunlight when they walk on a slab.
 * When firing arrows at the opposite corner of the slab, your arrows may clip through and hit the block behind it.
 * When walking with 50-100% of your body over a slab, whilst being at the high of another block, the walking sound effect for the slab type will play, rather than the one which you are actually on.
 * A single slab cannot be made into a double slab if there is another solid block directly above the single slab. This is because Minecraft places the slab normally first, then realizes it's on top of another slab and combines them.
 * It is impossible to be suffocated by single slabs.
 * With Smooth Lighting on, a slight amount of light can be seen passing through the sides of slabs. This does not affect mob spawning.
 * If a slab is placed on ice, it still has the "slippery" effect.
 * If half blocks are placed next to TNT, the damage is significantly reduced.
 * Neither single nor double slabs displace item entities.
 * When exiting and reentering the game while standing on a single slab with empty space below,you sometimes fall through the slab.
 * Client crash when data value "44:4"(slab with 4 damage) is moused over in inventory.
 * When putting a slab on a slab which has another slab below it (or more) all slabs combine into one double slabs block, thus losing one (or more) slab in the process. Also reproducible in 1.6.6 server.
 * If a single slab is placed on a lower block and another single slab is placed next to but one block up from the lower slab, and the player attempts to walk diagonally across the lower slab and towards the higher one, there is a chance that the player may no-clip through the higher slab and fall through it. Example: video of the bug

Snow

 * In snow biomes, water and lava lakes can generate below the snow and leave some of the snow floating. Players will fall through this floating snow.
 * Beds cannot be placed on snow.

Sugar Cane

 * Visual bugs with Sugar Cane looks like they float. However, you can still see the selection box.
 * If you place a Sugar Cane under the water with a water block one block lower next to it, the sugar cane will stay there with out breaking.

Tools

 * Axes do not break certain wooden blocks faster than hands, like you would expect. These blocks include wooden stairs, fences, wooden doors, signs, crafting tables, note blocks and jukeboxes. You can break blocks faster, try it punching stone!



Water

 * Water sometimes doesn't flow into newly generated areas (usually when a cavern is being generated near a body of water).
 * In a newly generated area, sometimes the water's height does not match water height of the old area (in the same body of water)
 * Unlike Glass, other water blocks are invisible when viewed through a waterfall, even though there is air in between.
 * Water source blocks do not regenerate over non-solid blocks such as glass or other water.
 * When opening your inventory when swimming, you can only move left or right until you move.
 * Upon entering a newly generated map, water may be found floating in midair.
 * Water lakes will not freeze automatically at map generation.
 * Water in Desert biomes may turn to ice despite being in the Desert.

Weapons

 * While trying to aim the Bow, the animation of the bow and arrow does not appear. This is however clarified that this rarely happens.

Weather

 * When lightning strikes, ice, water, portals, rain, snow, and other particles behind it become see through.
 * When rain puts out a fire on Advanced OpenGL the area will sometimes stay lit.
 * Sometimes rain and snow both fall at the same time in the same biome.
 * Rain and snow fall above the cloud layer.
 * Rain does not pass through signs.
 * Rain can't be heard over layer 95, which is under the cloud layer.
 * On "Fast" graphics setting, rain still creates particles on contact with the ground, causing slowdown on computers that can't handle it.
 * Rain passes through slabs.

Mac OS X

 * On some Mac OS X Systems, the World Select screen will not appear at all, making the game unplayable on those Mac systems.
 * On MacBooks with GMA 950's Minecraft will Start Locking up randomly and cause delayed and choppy, 8bit sound even when the game is running smoothly again.
 * In other cases, the Mojang AB logo will appear green and the title screen and the game in dark areas will appear red or transparent.
 * Since version 1.3, on some Mac OS X systems, when the player closes the game (clicks the X button on the window) the computer will freeze up completely. The mouse will still move, but nothing else responds, forcing a hard shut down and restart. In addition, the system does not acknowledge the issue (e.g., no crash report window, no system.log entries). When on an afflicted computer, this rarely may not happen (often after a reboot or game update).
 * Afflicted systems seem to be older 32-bit Intel Macbook models, such as those made in and around 2007.
 * A work-around is to save to the title screen, and then Force-Quit Minecraft, instead of properly closing it.
 * It appears to only affect users with Intel GMA 950 graphics processors, known for its incompatibilities with 3D games.
 * Under MacOS X, Minecraft does not respond to either the Quit item in the Minecraft menu or it's shortcut, ⌘Q. This can be fixed by closing the window, then quitting Minecraft.
 * Pausing the game and expanding the window (+) as soon as the map is loaded causes a kernel panic, forcing you to restart the computer.
 * The game runs slow on Mac OS X 10.6 using a NVidia GeForce 320M graphics chip (it has some lags getting more and more as you play), however it runs with 60 or more FPS (average 120) on Ubuntu, using the same system. (Driver support fail) This bug isn't fixed with Mac OS X 10.6.8, though it includes new graphics drivers.
 * Minecraft uses an 8-bit depth buffer on many macs, including brand-new high-end ones. This makes distant objects look terrible! It can be remedied by specifying the size of the depth buffer when creating the PixelFormat for the OpenGL context. Changing Display.create to Display.create(new PixelFormat.withDepthBits(32)) in net.minecraft.client.Minecraft.startGame fixes the problem. Look at this before and after screenshot and notice the huge difference.
 * On some Macs, there is no audio, when you turn on the sound on Minecraft, the game hangs for a minute, then returns to normal, but still no audio. Otherwise, try holding F3 then press S while you are in Minecraft.
 * Since a recent update (roughly on 5/1/2011) to MacBook Pros (2011 model), there are patches of white in the sky on many users clients. Additionally, the health bars of items are white and the background to the inventory and options menus are completely white. Also, when you sleep it becomes all white as well. Force updating the client does nothing to help nor does updating your Java.
 * One user noted that after removing the Minecraft folder in /Users/nickname/Library/Application Support the problem is fixed until you change something in the gfx settings of Minecraft (turning on OpenGL). After you change the settings the only way to fix it back is to remove the folder again (manually switching to the default settings doesn't fix it)
 * Another user noted that it can be fixed by turning off Advanced OpenGL and then restarting Minecraft. However, the problem returns when the user turns Advanced OpenGL back on. Since the game performs better with Advanced OpenGL on, users still consider this a bug.
 * After researching the bug, one user found that many of the effects of the bugs are from Intel's poor driver development for the Intel HD 3000 GPU. This GPU is only used in the Macbook Pro 2011 13" model and thus the reason for the glitches.  As for the fix, after  speaking with Intel they said that Apple develops the drivers for their Mac GPU's and not Intel themselves.  As of 7/21/2011 this bug still exists.  However, it seems that with the release of Lion OS X, the drivers might have been developed more.  According to the change log of the OS, no further release of an Intel driver is mentioned, however on Minecraft with OpenGL turned on, it works fine, EXCEPT that it has created new glitches! In one users inventory, the sides of blocks are blacked out and so are the sides of animals at random.
 * Sometimes while trying to close the Minecraft Client in Mac OS X with the X button, it will freeze up for a few moments, while you can still move your mouse around and click, the X button will freeze, then allow you to click it again.

Linux

 * If you close the minecraft window, sometimes the system logs out for no apparent reason.

Server Crashes

 * Players dying and dropping large numbers of Xp/Orbs causes severe lag and can crash a server. There have been several reports indicating that the world was corrupted by this crash and the world is now unrecoverable.
 * If the server is still a little bit responsive one can try to collect the dropped orbs. preferably with one client alone on the server. the more orbs recollected, the more will the server recover. It can take quite a long time to collect all the orbs (60 minutes in one case)
 * It is possible to delete the Xp/Orbs through an external editor such as MCEdit.
 * Exploring new chunks on a server can cause severe lag, possibly crashing the server.
 * Attempting to connect to a 1.7.3 server with a 1.8 client, can crash the 1.7.3 server.
 * If a player is killed by an arrow from a Dispencer, the server will crash with a NullPointerException.
 * Shift-clicking with a dispenser dialog open will crash the server (at least in creative mode).

General
--124.123.158.103 13:37, 14 September 2011 (UTC)
 * If a player has respawned, he can place blocks on the block he is currently standing on. This will not decrease the block count in his inventory, effectively cloning blocks. This bug only occurs with non-opped players.
 * Full server world saves do not reliably save the entire world. This can be proven on a single person private server with whitelisting enabled when attempting to do a full server save via:
 * 1) Disabling incremental level saving with 'save-off' on on Minecraft console.
 * 2) Forcing a full save to disk with 'save-all' on on Minecraft console.
 * 3) Archiving and saving the archived world with 'tar -xvzf save.tg world' or '7z a backup.7z worldfolder/' on shell in secondary system console.
 * 4) Turning back on incremental level saving by doing a 'save-on' on Minecraft console.
 * Enormous, cuboid areas (usually one or two chunks) of unfinished map open in random places. Caves, minerals, water, lava and mobs are visible when a Player peers into one of these voids. These areas cannot be walked on, causing a "[user] moved wrongly!" message to appear in the Server; however, players can ride minecarts through them with relative ease. Players can, however, walk "into" one of these voids (if it appears in front of him/her) resulting in the player falling repeatedly until the map renders itself. If the void appears in the middle of water, Players can "float" over the void using a boat. Placing a torch next to one of these "void holes", dumping lava or water nearby, or disconnecting and reconnecting to the server will make the land inside of them reappear. These have become significantly less common since the 1.3 update.
 * Occasionally, the level.dat file is re-written, causing Minecraft to generate a new spawn. Also occurs in SSP.
 * Some Ambience sounds do not play in SMP.
 * The world data and the inventory of a player are not saved synchronously. If a player puts an item in a chest and the server crashes, the item will be both in the chest and the inventory of the player (duplicated).
 * Some players have issues where they can send information to a server fine, but have large amounts of lag when receiving information from the server. This results in SMP being unplayable for players who experience this bug.
 * Sometimes the client is slightly off on the position of other players, causing them to consistently appear slightly off of their actual position. This can cause players to appear to be inside floors or walls.
 * When collecting a block/item on the ground, the icon in the inventory's hotbar does not distort for a short time.
 * Thrown snowballs, eggs and fishing rods have no effect on players, only on mobs.
 * Sometimes when connecting to an SMP server, an 'End of stream' message or 'Bad login' message appears. After this message appears, the Minecraft client may need to be restarted or left alone for roughly 5 to 10 minutes before it will work.
 * Notably with Sand, the sand may continue to hover in the air after being mined out and continue to bob up and down. Placing a block in the spot does NOT override this. Items have the same behavior, but they can be picked up when standing above the affected area.
 * Occasionally players will become invisible to each other at random times for no particular reason and will subsequently reappear just as randomly. Players may still interact with each other (damaging each other, mining terrain, etc.) but will be invisible. An entertaining video example
 * If you disconnect while you are falling, you will not take fall damage, after you reconnect. The same applies for any form of damage. This is due to the 3 second invincibility period after respawning/logging in.
 * When connecting to a server, the player's disconnect position may be changed or rounded. This can result in the player position moving vertically to the closest 1x1x2 open space directly above the rounded coordinates.
 * Deaths or Player kills are not recorded in the statistics when the player dies.
 * People are sometimes unable to talk on chat in every single server.
 * Blocks regenerate during a lag, so players can suffocate in them.
 * If the server side does not have large bandwidth(i.e. 100 Mbit/s) the clients can experience severe lag for about a minute and then get automatically disconnected show a error on server side "disconnect.overflow". Possibly due to sending small packets at a extremely rapid rate overwhelming the client
 * Server incorrectly reports "Failed to load ip ban list" when started with a missing ops.txt file.
 * When you died and wait for a while, the server will say: [user] lost connection: disconnect.genericReason. If that occurs, if you click on respawn, you will see an End of stream error and makes you disconnect from the server you were playing in.
 * When whitelist is Enabled on the server you will get "Communication error" in the server list, this applies even if the user is White listed.
 * Player spawn location seems to be erratic.
 * Chests are being rotated visually leaving a see through block.
 * Chests are black and unlighted until opened.
 * Chests are being rotated 180 degrees to face away from the player when before they faced the player.
 * Chests will sometimes remain open when no one is using them.
 * Spawn points can be generated at the bottom of deep ocean biomes,sometimes deep enough to keep drowning players not in creative or unable to teleport leaving them in a death loop.
 * Sometimes when you try to log in on a Server, your Minecraft client will freeze at "Logging in..." in a few minutes.

Achievements

 * Some Achievements may not show up when you get them. (Which?)

Arrows

 * Seconds after an arrow lands on a block, it will "teleport" on top of the block.
 * Arrows do not deal a critical hit even when fully drawn.

Beds

 * Sometimes when a player is sleeping and other player walks on that sleeping player the sleeping player will fall through the bed and the floor.
 * Trying to get into bed while sneaking disconnects the player(Illegal Stance).
 * If someone uses their bed in SMP, other players may get disconnected(Unrecognizable Packet ID: 17).
 * Attempting to hoe under a bed that would experience the monster spawning error would kick the player that used the hoe (illegal stance).
 * When right-clicking on a bed constantly before it is nightfall, the server may register that the player enters the bed, while the client believes the player is still not in the bed, causing the error message, "This bed is occupied," even when it appears there is no player inside. Other players will see the affected player moving around while he is in a sleeping pose.
 * The above "this bed is occupied" glitch sometimes also seems to occur if a player tries to enter a bed mid-jump.
 * If you try sleeping in a bed on SMP server while standing on it, it will start giving message "This bed is occupied" and you will be allowed to freely walk, but you will be really sleeping. Players will see you move but you will be lying down. You cannot trigger pressure plates while "sleepwalking", nor pick up items.
 * A right-hinged door (when looking from the outside) will act as though there is no door present and as a result, you will be attacked while trying to go to sleep.
 * When a player goes to sleep in bed between the trunks, it is shifted.
 * In some cases, even when there is a block protection on a bed, you are still able to destroy someone's bed by first destroying the lower part, and after that the upper part. Please note that this is not the case on some servers, because of 0% lag.
 * In SMP if you sleep in a bed someone else placed, a monster will spawn next to the bed of any one random person who is in bed. This can be fixed by breaking and replacing the bed.

Boats

 * If you ride a boat over a chunk of water which did not load properly ( ex. the water is really there, but you can't see it and can see through the whole world ), the boat disappears.
 * Standing on a boat causes jittering of the player, similar to the old fence bug.
 * When a Boat gets damaged (by a player), it does not shake.
 * If you see a player riding in a boat, it sometimes looks like they are running in the boat, rather than sitting.
 * If you exit a boat, you may get stuck standing on top of the boat, constantly falling and being reset by the server. This is similar to how fences used to act. You can get off the boat by getting out while it is moving, as the boat will slide out from under you and eventually allow you to fall into the water. However, this may kick you from the server with message "flying not allowed"
 * The boat turns in intervals of about 10-20 degrees, making turning extremely difficult in tight spaces. In between intervals of turning, holding left or right will cause the boat to strafe left or right, respectively.

Cactus

 * 1 block high cacti do not always appear, causing invisible blocks of pain. The outline of the cacti cannot be seen, so it is not a rendering issue. Destroying the block underneath the cactus causes the cactus to drop. Disconnecting and reconnecting forces the cactus to appear.
 * Sometimes only the topmost block of cacti show, making them float. walking beneath them is possible, but it causes pain to the player.

Compass

 * When spawning or crafting a compass in SMP it does not take you to your spawn, it creates a totally different 'north'.

Detector Rail

 * When placed immediately next to a track switch, will crash the server. [!!]

Farmland

 * Flying low over tilled farmland will sometimes revert it back to a regular dirt block requiring you to re-till it. Basically it acts like you are walking on it.

Furnaces

 * Furnaces stop smelting items during a severe lag.
 * Furnaces occasionally turn to another direction after being placed. Appears to be random.

Food

 * When a player eats, their hunger bar will go up by more points then it should and consume more food than the player intended (1.8.1)

Jukeboxes

 * Setting a jukebox on fire when it is playing a disc may cause the game to crash.

Lightning

 * If lightning strikes a painting, it causes a server exception and crashes the server. (Caused by net.minecraft.server.EntityPainting.damageEntity)

Maps

 * When multiple players are using the same map, the orientation of the arrow only represents the direction the current user is looking, not the player the arrow is representing. When the user of the map rotates, all the arrows rotate.
 * When the server's view distance is set to a lower number (5) walking with a map may cause the server to lock up . Setting the view distance back to the default of 10 fixes this.
 * If a player moves too quickly horizontally while holding a map (usually from flying or teleporting), chunks will stop loading for that player and possibly other players, eventually kicking them off of the server due to timing out. The kicked players will not be able to log back into the server until it's restarted, despite there being no such problem for other players.
 * Some users have reported their maps becoming glitched and do not display properly if they relog with the map in their inventory. Giving the map to another player and having them give it back or putting the map in a chest and taking it out again seems to fix this until they log off again.
 * Creating a map with shift-clicking on it creates map_0 and not a new map [possibly intended]

Mob Spawner

 * If a mob spawner is destroyed while in Creative Mode the fire effect will remain even if another block is placed and destroyed at its location.
 * When a sign is placed at the destroyed mob spawners location it will cause the game to crash.

Minecarts

 * Engines consume coal but do not move under their own power, making them useless.
 * Empty/Storage Minecarts start to behave strangely when they are too far away from the Player. They disappear completely, disappear until Players disconnect and reconnect, or suddenly stop on tracks despite having sufficient momentum.
 * Minecarts load before terrain sometimes causing them to be invisible until they are interacted with. Large transit systems and door water boosters are examples of when the issue occurs. (log out/in to reproduce).
 * Minecarts being destroyed do not wobble.
 * When you're trying to send a Powered Minecart to a destination that is farther than the loaded chunks, the minecart stops after a while and never reaches its destination. But if you approach the powered minecart, you can see it moving again : you have to stay close to it.
 * An unpowered Powered Rail does not stop or even appear to slow down a Minecart when it is travelling very fast. Three unpowered pieces in a row seems to stop it every time.
 * If a mob spawns on a powered track circuit it will be pushed around it.
 * Stacked Minecarts glitch out and jump up and down.
 * An empty minecart too far from a player on powered rail will come back, when it would stop at the end had a player been with it.
 * A minecart ridden off a jump damages the ridder just as they leave the jump, not when they land. (witnessed after full boosting by a powered track)
 * An empty minecart falling more than 3 blocks (enough to deal damage were a player riding in it) and landing on tracks will cause any subsequent rider of that cart to take damage when any fall occurs, regardless of height. If the cart is removed and replaced on the tracks, the damage does not occur. Easily reproduced by placing a minecart on a powered downhill rail 5-6 blocks above a loop-track with a 3-block fall. Sitting in a cart on the 3-block fall track normally causes no damage, but starting the cart on the powered rail at 5-6 blocks, landing it on the 3-block fall loop, and getting into the cart and starting the loop will cause damage on the 3-block fall.

Mobs, Hostile

 * Shooting animations (Ghast fireballs/opening mouth and eyes, Skeleton arrows) are not always visible. The sound of these actions (Ghast scream and Skeleton "twang") cannot be heard either.
 * Ghasts' fireballs occasionally do not explode, only lighting a small area on fire.
 * Sometimes mobs freeze in animation and can not be hit. They disappear after about 2 minutes. They are client-sided, so no other players will see them.
 * Some users are reporting mobs will be invisible, but can still attack you. On update 11/24/2010 Notch explained that to see invisible mobs, players must set their difficulty to the server side difficulty or higher.
 * Sometimes when the character dies, monsters will stay loaded client-side and not be loaded on the server side.
 * Sometimes players can hit mobs multiple times before the server registers the hit. The hits will then all register at once and the mob will be subjected to several knockbacks at once, flying into the air.
 * When a mob dies, its corpse sometimes is still visible in the red death animation and vibrates.
 * The lower half of mobs can not be hit with a melee weapon when you are 1-2 blocks below them. They can, however, be hit from directly underneath.
 * When a mob chases the player, it does not look directly at the player. This is caused by server lag.
 * Melee Mobs (and creepers) can attack you from farther than normal, not due to normal server lag.
 * Mob spawners still work when the server is set to creative, but hostile mob spawning is disabled.

Mobs

 * Sometimes, Mobs of all types sink of 1 blocks in the ground, resulting in almost invisible mobs and darker mobs.
 * Sometimes mobs take no damage falling into running water less than one block deep, even if the player takes over 10 damage falling the same distance into the same water.
 * Mob spawn rate seems significantly lessened when server view-distance is under 10, possibly related to mobs seeming not to despawn from chunks unloaded earlier than usual due to the setting. Set view-distance back to 10 (default) for proper behavior.
 * Mob spawners always show a pig rather than the mob they actually spawn.
 * If a mob spawner is placed on grass, it will spawn client-side ghost pigs that cannot be killed.
 * If an Enderman is damaged by a creeper explosion, and they are then looked at and become hostile, they will glow at light level 15 but will not light up the surrounding area.
 * Endermen can pick up Bedrock (intentional? SSP, too?)
 * In most cases, endermen will only become aggressive when you look about 2 blocks above their head, but they will also still fight back if you attack them.
 * Endermen do not open their mouths on SMP, even when aggressive.
 * Hostile mobs spawn on servers set to peaceful (i.e. spawn-monsters=false) from dungeon spawners.
 * Occasionally Ghasts will remain where the original mob died. They are stationary and have no collision. These are client-side, so other players will not be able to see them.

Mobs, Passive

 * Squid moving on the bottom of a body of water make the normal "footstep" sound.
 * Occasionally after dyeing a sheep they will still yield wool in their original colour (i.e. white).
 * If you look towards an Enderman with a Ghast between you and the Enderman, it will attack the Ghast, except it will not take damage. The Ghast will still attack you though.

Mobs, Friendly

 * Occasionally, Wolves can disappear on SMP Servers, disconnecting and reconnecting fixes this.
 * Sometimes after reconnecting to a server, wolves that were previously sitting will appear to be standing. They still behave as they are sitting.
 * When wandering a significant distance from a sitting wolf, it teleports to your location and becomes active.
 * Sometimes after you go to sleep or are away for a while, your wolves will appear standing, although they act as they are sitting. This happens in both SMP and SSP, but more common in SMP.
 * After the 1.6 update, some tamed wolves will act as wild wolves. They don't stand up and attack you after you hit them.
 * On at least some 1.8 SMP Servers, wolves never appear. The same worlds spawn wolves in single player.

Nether

 * The Nether and the Overworld merging together in chunk generating.
 * When you are burning and go through the portal (Nether -> Real World) and then return back into the Nether (not burning) a new portal appears in the near (side by side or one above the other). This can be handy to farm obsidian if you have another portal in The Nether.

Note Block

 * Note blocks and especially note-block-combos tend to react really easily on server's lag. Unable to make any longer noises / songs with note blocks on multiplayer.

Paintings

 * When copying an SSP world onto an SMP server, paintings are removed in the transition.
 * Paintings can be destroyed in spawn-protected areas.
 * When placing a painting behind a stone button both become locked and can only be removed by destroying the supporting block.

Pistons

 * When Redstone (dust) is placed on a block behind a Piston and activate the piston does not respond - as expected. Removing the piston then replacing it in the same spot will then activate it. It may be easier to watch this video example
 * Items ejected when a piston pushes a block in their place cannot be picked up.
 * When pulling an Ice block with a sticky piston it cases the water to 'leak out' pushing it back then stops the water and causes the piston head to become invisible. (Still existing in 1.7.3 after the 'fix') video examplesecond example
 * When two pistons (one sticky and one regular) are used at right-angles to each-other a block deletion/disposal glitch is created. This also reacts strangely to Ice blocks. video example

Portal

 * As of 1.6.X, there is a chance of Minecraft's renderer to stop functioning (you can hear the audio going normally, and the server still registers you as playing), leaving you with a black screen, when you use a portal in SMP. Rejoining the server fixes this, but is a workaround.
 * When a portal is placed along the edge of a chunk (for example, the entire portal is along the x:-31.5 coordinate), and is used as a DESTINATION portal (as in, it is the portal you're teleporting TO) you will frequently find yourself "falling" before the chunk loads, and will actually end up "stuck" buried up to your waist in the obsidian base of the portal. This results in you being "stuck", bouncing up and down. You can usually free yourself with much struggling and jumping, but it's difficult. (Verified on a 1.6.6 unmodified server, with no client-side mods. - Moleculor 02:05, 13 June 2011 (UTC))
 * Going through portals repeatedly will leak memory, eventually leading to the Out Of Memory crash screen.

Powered Rails

 * When riding uphill in a minecart on powered tracks at full velocity, the cart will turn back.

Redstone

 * While destroying a block, quickly applying redstone repeatedly will cause you to see textures of different blocks. Also, quickly removing redstone AND attempting to mine the block it is on has a small chance to make it show the glitched grass texture on top of the block.
 * Redstone Repeaters occasionally become locked if their chunk becomes inactive while they are in their powered state.
 * The redstone repeater has poor block updating when powering into solid blocks. Note blocks won't sound, doors won't open/close, ... The repeater doesn't follow the standard 2 block update radius, but rather just 1 block update around it.
 * In SMP, redstone torches on chunk edges disappear when there is a block update nearby, or when the torch becomes targeted by the 80 random block updates that are scheduled every game tick.

Signs

 * When a sign is placed in multiplayer and text is entered (but not finalized), and a torch is placed within 10 blocks of the player who placed the sign (not the sign, but the player), the entered text disappears. Interestingly, when a torch is placed within 10 blocks of the sign placing player BEFORE the sign is placed, any subsequent text entered will not be erased by torches placed OUTSIDE the radius of the first torch, but text will be erased by torches placed INSIDE the radius of the first torch. Oddly, this behavior only seems to occur with torches, though these tests were not exhaustive of the minecraft block set, and further work should be done to verify this claim. Situations with the same problems as the above: cobblestone regenerated from a cobblestone generator, the change of redstone charge and at the bottom of the map with Bedrock, Obsidian and chests present.

Time

 * The server command /time breaks 'clock based' circuits. Using a bed to change time does not affect the clock generators. Restarting the server fixes circuits until the /time command is used again.
 * When the /time command is used by 2 people at the same time, the time may not change at all, it suddenly can become dark, no matter what value is entered, or the server lags so much it needs a restart. This mostly happens on Hamachi/slower servers.

TNT

 * A TNT block meant to drop will enter a repeating fall animation (but not actually fall) when lit.
 * If a lot of TNT is lit, some TNT may explode but leave behind an image of an exploding TNT block that is almost completely white, and will hover in mid-air while repeating the falling animation. The ghost TNT will not disappear unless the player disconnects and reconnects. (This is a client-side TNT entity)
 * You cannot use the pushing force of TNT to jump higher in SMP.

Trees

 * Trees that have grown recently, especially packed together in a tree farm, sometimes don't update the client with the leaf positions. This creates "invisible" leaves that the player can't walk through and makes navigating tree farms an annoyance.
 * Using bone meal to quick-grow trees will sometimes cause "floating" trees to grow with the sapling still at the base. Removing the sapling or using more bone meal can cause the tree to grow into an enormous bundle of leaves with no log base. These leaves will now respawn immediately after being harvested. The only way to remove these glitched leaf blocks is to burn each block individually (fire will not spread for some reason) OR set the floor below the leaves on fire OR build an umbrella above it, the shadow seems to instantly vanquish the leaves. - This glitch is vastly more common when quick-growing trees under another trees foliage. Again, disconnecting and reconnecting will reset these "ghost trees."
 * Planting a sapling and waiting a bit will sometimes yield tree trunks with weird distributions of leaves, and in some cases, no leaves at all. Trees can also grow but be invisible, making it impossible to traverse a tree farm after a while. Rejoining the server appears to make invisible trees visible again and fire will swiftly cause phantom foliage to be made manifest. You can also place a torch to make the phantom foliage appear.

Water

 * Client and server breath meters are not synchronized. This sometimes causes the client to register the player has gotten air, but the server to start drowning early.
 * In some underwater areas there are lines of lighter spots at the bottom the water, likely on the edge of chunks where the next chunk over used to be empty space (causing light from the side to reach the bottom on the edge of the chunk).
 * It is possible to stay underwater without drowning using a bucket. Right-clicking on the right water block with an empty bucket creates an air block for a short time which is sufficient to reload the breath meter, thus it is not easy to hit this right block.

Weather

 * Rain passes through slabs.
 * When logging on to a server during rain, the rain passes through the blocks in the chunk in which the player was standing when he/she logged on.
 * Rain may pass through wool blocks.

Portal

 * If you put wool outside of a nether portal, it may randomly vanish.

Creative Single Player

 * Arrows, snowballs and eggs decrease in number when thrown/shot, unlike other items.
 * Shift-clicking an item gives you 64 of that item instead of going directly into the hotbar.
 * If you fly too high, you lose your skin in a lag.
 * You have an inventory, but you can't open it without a chest, crafting table, furnace or dispenser.
 * You cannot equip armour.
 * Blocks and some Items are Missing; such as Monster Spawner, Mushroom Blocks, And Charcoal.
 * Items moved to chests/dispencers only count as 1.
 * Only mod items show in the creative selction screen, mod blocks do not.
 * Any breaking of blocks not directly broken by the player results in the dropping of the item specific to that block. This includes such things as water knocking out redstone components/wire.
 * When you try to extinguish fire, you will extinguish the fire and break the block below it.
 * When in Creative mode you can enter boats and minecarts from any distance and through walls.
 * You'll lose your flying ability if you are sitting in water that flows downwards.
 * Lava and Water bucket's offers a unlimited resource, but a bucket doesn't have the ability to pick up unlimited amount of Lava and Water, making it annoying to pick up it by bucket (once picked up, they also deliver unlimited resources)
 * Paintings can be destroyed from any distance and through walls.
 * When breaking a painting, the block behind the painting has a chance of being destroyed (this can be avoided by delivering a very short mouse click to the painting, which can be rather difficult). This renders the process of trying to acquire a particular painting design very tedious.
 * If a painting is in the crosshair at all, even through walls, you can't place blocks at all. This can make building walls in a structure that has paintings in it very annoying.
 * If you fly very high, the block you hold may shake.