Crashes are unexpected shutdowns of Minecraft. When Minecraft crashes, it typically closes immediately, though it may show an error report marking the location of the exception that caused the crash. A sign of a server crash is a "Saving chunks" or "Shutting down internal server" screen. The most common cause of crashes are mods, preexisting bugs, and updates. 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. Crashes can sometimes cause the corruption of save files if the player is not careful enough. Because of this, it is highly recommended that the player regularly keeps a copy of their save folder (located in the %appdata%/.minecraft directory on Windows systems or ~/.minecraft/ in linux), to reduce their losses should a world become corrupted as a result of a crash. Large TNT explosions can also cause crashes.
Crashes used to have an error report screen, but that feature has been removed. Yet sometimes, an error report can quickly flash right before the game closes. Minecraft occasionally does this on startup, except it stays there, not allowing the player to play the game.
A tutorial exists for obtaining the report file generated by the game when it crashes so that the player can share it for diagnosis.
Causes of crashes
Crashes can easily occur due to mod conflicts, wrong versions of mods, or buggy mods. If the player has installed several mods, if using the older launcher, they should try renaming the "bin" directory in the Minecraft folder, then start Minecraft (Or replace the current minecraft.jar with a clean minecraft.jar from either a clean backup, download a jar file from the internet or force update the game should cause the player to get a new clean jar file.). A new bin folder is created. The player should remove the problematic mod. Now, the player should install each mod they 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, the player should either remove the mod they determined to be causing problems, or repeat the first step, except without installing the problematic mod.
Problems with the player's computer's hardware can also easily cause crashing, or buggy behavior. If this is the case, it's likely the they are 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 the player is indeed experiencing crashing or visual corruption in other games as well, the first thing to check is whether their computer's vents are blocked, or clogged with dust (which inevitably occurs over time). Dust or vent/fan blockages can cause 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 the player is using a laptop, they should make sure any vents on its sides or bottom are neither blocked or filled with dust. For a desktop, the player should check obvious fan locations for blockages, and use a flashlight to peer inside the case. If there is much dust, or any internal fans appear to not be spinning, the player should either take their computer to a repair shop for a "tune-up" (mention that the player suspects there is overheating problems), 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 the player to accidentally damage your computer).
If the player's computer appears to not be suffering from overheating related issues, another cause of game crashing could be a damaged component, especially either the RAM, or the video card. If the problem just recently started occurring, and the player has not recently installed any major updates or software such as Anti-Virus suites, the player may want to take their computer to a shop to have it tested, or they 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 the player's computer meets the basic system requirements of Minecraft, there is a possibility that their hardware might have unique issues, one being the use of Intel GMA (Graphics Media Accelerator) cards, known for issues with OpenGL. However, if the player's graphics card is one of those cards, they can still play 1.7.10 and 1.8.
Though unlikely, unrelated software can conceivably cause crashing in games such as Minecraft. The most likely candidates are User Account Control (Windows Vista, 7 and 8), Gatekeeper (Mac OS X Lion and Mountain Lion), 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 the player recently installed an application such as AV software, they should try disabling it. If Minecraft stops crashing, they know the AV program is the perpetrator. The player can either remove it (not recommended for security reasons), or configure it to ignore Minecraft's folder and executable. If they are unsure of how to, they can look up some tutorials on the Internet. Alternatively, system processes can often consume a lot of resources (most infamously Windows 10). If there is too much system overhead, there is really not much one can do besides attempting to disable those processes or switch operating systems. Another certain crash is to set all the files in the .minecraft folder to read-only.
JVM Crashes are crashes where the Java Virtual Machine, the program that runs Minecraft itself, crashes. These are almost always caused by doing large, potentially groundbreaking operations like moving many blocks, exploding a lot of TNT, or other memory or processor intensive activities, and additionally almost always are caused by running out of RAM. These are unique in that the crash message is quite different, having come from the JVM's crash handler rather than Minecraft's handler. Because of this, they do not generate a crash report in the .minecraft/crash-reports directly, but rather one directly in the .minecraft folder, with name "hs_err_pid<PID>.log" where <PID> is the Process ID of the JVM at that time. Additionally, these crashes cannot be stopped by mods that "catch" Minecraft crashes, like VanillaFix.
The player can also trigger a crash manually by holding F3 and C. This is used for debugging, and is the safest possible crash. On some computers, pressing fn key enables the F3 key.
Ticking block entities
The rarest type of crashing possible is that of a ticking block entity.
Witty comments are phrases shown at the top of crash reports generated using the process shown earlier in this article. They do not show on crash screens and are similar in nature to splashes. They can be changed by changing the player's minecraft.jar .class files. They are selected using the system's time in nanoseconds.
|Who set us up the TNT?||A snowclone of "Somebody set up us the bomb" from a badly translated English version of the 1991 game Zero Wing.|
|Everything's going to plan. No, really, that was supposed to happen.|
|Uh... Did I do that?|
|Why did you do that?|
|I feel sad now :(|
|I'm sorry, Dave.||Part of the famous quote "I'm sorry, Dave. I'm afraid I can't do that." from the movie 2001: A Space Odyssey.|
|I let you down. Sorry :(|
|On the bright side, I bought you a teddy bear!|
|Daisy, daisy...||A second reference to the movie 2001: A Space Odyssey, where the Hal 9000 sings a song as Dave tries to turn him off.|
|Oh - I know what I did wrong!||A cross-reference to the "I just don't know what went wrong :(" witty comment.|
|Hey, that tickles! Hehehe!|
|I blame Dinnerbone.||Dinnerbone is a Mojangsta.|
|You should try our sister game, Minceraft!||References the easter egg in Minecraft where the title screen has a 1 in 10,000 chance to rearrange the C and E in the title.|
|Don't be sad. I'll do better next time, I promise!|
|Don't be sad, have a hug! <3|
|I just don't know what went wrong :(||A cross-reference to the "Oh - I know what I did wrong!" witty comment.|
|Shall we play a game?||Quote from the movie WarGames when the character David Lightman first contacts the computer Joshua.|
|Quite honestly, I wouldn't worry myself about that.||Another quote from from 2001: A Space Odyssey. HAL's answer to Frank: asking: Well of course I know all the wonderful achievements of the 9000 series, but, uh, are you certain there has never been any case of even the most insignificant computer error?|
|I bet Cylons wouldn't have this problem.||The Cylons are a recurring part of the show Battlestar Galactica.|
|Surprise! Haha. Well, this is awkward.|
|Would you like a cupcake?||Probably a reference to Girl Scouts.|
|Hi. I'm Minecraft, and I'm a crashaholic.||The common introduction in Alcoholic's Anonymous meetings (and other addiction help groups) where the current speaker starts off with "Hi, my name is _____ and I'm an alcoholic".|
|Ooh. Shiny.||The game Terraria features an advancement called "Ooh, shiny!" in which the player mines their first ore.|
|This doesn't make any sense!|
|Why is it breaking :(|
|Don't do that.|
|Ouch. That hurt :(|
|You're mean.||This was one of the quotes from the Java Edition 2.0 April fool's joke.|
|This is a token for 1 free hug. Redeem at your nearest Mojangsta: [~~HUG~~]|
|There are four lights!||From Season 6, Episode 11 of the show Star Trek: The Next Generation where Capt. Jean-Luc Picard is captured and tortured by Cardassians, which itself is a reference to a torture scene in 1984 by George Orwell.|
|Witty comment unavailable :(||Displayed if a comment fails to get selected, which is rare due to the way the comments are coded. Ironically, this is a witty comment.|
|July 10, 2013||Hopper is launched.|
|July 14, 2013||Hopper implemented to the Minecraft launcher.|
|July 15, 2013||Hopper submits crash reports to the database.|