Java Edition 12w40a

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Minecraft 12w40a
12w40a Banner.png

Java Edition



Release date

October 4, 2012

Snapshot for



Client (.json)
Server (.exe)

Protocol version


12w40a is the tenth snapshot released for Java Edition 1.4.2.[1]


World generation[edit]

Swamp huts
  • New generated structure.
  • Located in swamp biomes.
  • Spawns witches.


NBT tags
  • Custom items can now be named using NBT tags (intended for custom map makers).
    • Using the NBT, it is possible to add custom names to items, as well as a lore list for that item.
  • Added superflat preset "Redstone Ready" with 52 layers of sandstone, 3 layers of stone and 1 layer of bedrock.



  • Texture has been altered.
  • Beam texture has also been changed.
  • Spreading has been nerfed to prevent infinitely spreading fires.


Eye of ender
  • Can now be used in superflat worlds, if the stronghold generation is enabled.


  • Now spawns in Swamp biomes at low light level.


  • Better management.
  • The pick block action now works on blocks that are represented as items in the inventory (E.g.: repeater, redstone dust, and tripwire).
  • Pressing the 1-9 hotkeys while hovering over an item will put that item into the corresponding hotbar slot.
    • If there is already an item in the assigned hotbar slot, the hotbar item and the selected item swap position.
    • When in creative inventory, a full stack of that item will be transferred to that hotbar slot.
  • In creative mode, players can now shift-click items between the hotbar and the survival inventory.
  • The left-click action will no longer open doors, pull levers, push buttons or open trapdoors.
  • When in creative mode, pick block on an item will pick up a stack of that item.




13 bugs fixed

  • Fixed the wither's starting explosion not being disabled by the mobGriefing gamerule[2]
  • Fixed a few crash bugs related to world generation, map item expansion, and other things.
  • Reverted previous lighting changes, which corrected such bugs as:
    • The Nether being extremely CPU intensive.
    • Map generation taking extremely long.
  • Fixed mob AI considering cobblestone walls as blocks of normal height.
  • Fixed a few texture oddities with the witch.
  • Fixed entities in water producing glitchy water sound.
  • Gaining multiple levels at a time will no longer play the leveling up sound over itself as many times as leveled.
  • Fixed the "A 64 bit Java installation is recommended for 'Far' render distance (you have 32 bit)" message being covered by the bottom 2 buttons.
  • Fixed pets teleporting around randomly.[3]
  • Fixed being unable to place paintings larger than 1x2 and them popping off if they have been placed before.
  • Fixed destroying blocks under you with Efficiency-enchanted gear.
  • Fixed potion spawners crashing the game.[4]