Crash



Crashes are unexpected shut downs of Minecraft. When Minecraft crashes, it typically closes immediately, though it may show an error report marking the location of the exception which caused the crash. A sign of a crash is a "Saving chunks" screen. The most common cause of crashes are mods and preexisting bugs. Attempting to modify the files of Minecraft or individual worlds, even with advanced editors, can also cause crashes. Crashes can also be caused by bugs in the game (e.g.: before the 1.6.5 update, shift-clicking an item into a full chest would crash the game.) Crashes can sometimes cause the corruption of save files if the player is not careful enough. Because of this, it is highly recommended that you regularly keep a copy of your save folder (located in the %appdata%/.minecraft directory on Windows systems), to reduce your losses should a world become corrupted as a result of a crash.

Crashes used to have an error report but that feature has been removed. Yet sometimes an error report can quickly flash right before the game closes.

Mods
Crashes can easily occur due to mod conflicts, or buggy mods. If you've installed several mods, try renaming the "bin" directory in the Minecraft folder, then start Minecraft. A new bin folder will be created. Now install each mod you desire one at a time, starting Minecraft and assuring that there is no crashing for each mod. Once the crashing starts occurring again, the last mod installed is likely the problem, or another mod simply does not work with it. Either way, either remove the mod you determined to be causing problems, or repeat the first step, except without installing the problematic mod.

Hardware Problems
Problems with your computer's hardware can also easily cause crashing, or buggy behavior. If this is the case, it's likely you're experiencing problems in other, unrelated games as well. If Minecraft is the only game experiencing issues, then it is unlikely to be a hardware issue.

If you are indeed experiencing crashing or visual corruption in other games as well, the first thing to check is whether your computer's vents are blocked, or clogged with dust (which inevitably occurs over time). Dust or vent/fan blockages can cause a problem known as overheating, which may not be severe enough to cause problems during normal computer use, but during more intensive activities such as gaming, the temperature may spike. If you're using a laptop, make sure any vents on it's sides or bottom are neither blocked or filled with dust. For a desktop, check obvious fan locations for blockages, and use a flashlight to peer inside the case. If there is lots of dust, or any internal fans appear to not be spinning, you should either take your computer to a repair shop for a "tune-up" (mention that you suspect there is overheating problems), which you will have to pay for, or read a few tutorials online related to computer cleaning (note that a computer's internal components are highly sensitive to damage from ESD (Electrostatic Discharge, basically a static shock), so it would not be difficult for you to accidentally damage your computer).

If your computer appears to not be suffering from overheating related issues, another cause of game crashing could be damaged components, especially either the RAM, or the video card. If the problem just recently started occurring, and you have not recently installed any major updates or software such as Anti-Virus suites, you may want to take your computer to a shop to have it tested, or you can do it yourself using tools such as "memtest86+", "Furmark", etc (however these tools tend to require a medium to large amount of computer knowledge).

It should be noted that even if your computer meets the basic system requirements of Minecraft, there is a possibility that your hardware might have unique issues, something especially common with laptops and OpenGL (the API used by Minecraft to display the game's visuals). If your laptop makes use of a "video-card" in the Intel GMA (Graphics Media Accelerator) series, which are notorious for experiencing issues with OpenGL.

Software
Though unlikely, unrelated software can conceivably cause crashing in games such as Minecraft. The most likely candidates are various types of Anti-Malware (i.e Anti-Virus, Anti-Spyware, Firewall, etc) software, which could either consume enough system resources to choke other resource hungry applications, or could cause issues as a result of their "Heuristic" real-time scanning. If you recently installed an application such as AV software, try disabling it. If Minecraft stops crashing, you know the AV program is the perpetrator. You can either remove it (not recommended for security reasons), or configure it to ignore Minecraft's folder and executable. If you're unsure of how to, look up some tutorials using Google.

Windows

 * 1) Make a new text file, and open it.
 * 2) Save the file with a name that can be easily recognizable and quickly found.
 * 3) Put the following code into the file:
 * 1) Save the file, but as a BATCH/bat file, or in windows 7, hit start then paste the code into the search bar, in windows XP go to your start menu and hit run, then type in the code above.
 * 2) Run the file (if you saved it as a batch file). This will make the game run in offline mode, but should get you the error.

Method 1

 * 1) Open mcpatcher.
 * 2) Click "Test Minecraft"
 * 3) Go into a singleplayer world or multiplayer server
 * 4) Commit a bug that crashes the game somehow.
 * 5) You should now get the error.

Method 2

 * 1) Go to Macintosh HD/Applications/Utilities and open Console.app
 * 2) Run minecraft and when it crashes the java log will be added to the console, which you can then select and copy

Linux
and watch the console output. You can select and copy it after making the game crash.
 * 1) Open a terminal (xterm, gnome-terminal etc.)
 * 2) Run

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