Getting Minecraft Crash Reports (Java Only)
The Minecraft launcher keeps logs of game events as they happen which can be useful for debugging errors or other issues that may occur within the game. There are five types of logs that can be obtained:
A crash report is generated when some form of error is thrown within minecraft or java, and Minecraft is not able to recover or exit safely. When Minecraft crashes, an error message like the one below is usually shown. 
Most of the time, Minecraft crashes when mods are installed but cannot be loaded properly, but Minecraft crashes can also be caused by other factors.
Crash Report
Step 1
Open the crash-reports folder inside the .minecraft folder. 
Step 2
Find the latest crash report using the year, month, and day using the indicators in the image below. 
Step 3
Select the entire contents (Ctrl-A or Cmd-A) of the file and copy it (Ctrl-C or Cmd-C). 
Step 4
Open https://paste.gg and paste (Ctrl-V or Cmd-V) the contents into the largest field. Put your Discord username into the ‘Paste name’ field, and a description (e.g. “Crash Report”) in the ‘Description’ field. 
Step 5
Click Submit Anonymously. On the next page, copy the URL from the address bar and give it to whoever requested the log. Wait for further instructions. 
Troubleshooting
Bad Gateway (500) Error on https://paste.gg/
Split the contents being copied/pasted into two parts, then try again. Give both links to the requestor in order.
Crash Reading 101
Is your game crashing? Well this page is made to help with that. Minecraft like any game has a tendency to crash with the smallest error when running mods. Here are a bunch of crashes from around the Pixelmon forums, compiled into one universal tutorial anyone can understand!
How to use this guide
- To identify the cause of a crash, look in the section of the crash report under «Description»; this section is near the top of the report. Once you have found this section, search for the first line of that section in this guide by looking down the list or by using your browser’s search feature (F8 on most browsers). An example of where to find this line in a crash report is shown in the image below.
- Each bullet point is a separate crash report, although it is possible for multiple different crashes to be caused by the same underlying issue.
- If your crash report doesn’t match any of these issues, post the full crash report in a website such as Pastebin, and post the resulting link in either the Pixelmon forum’s support tracker or the Pixelmon Discord’s #log-upload channel.
How to find crash logs
If you close the launcher containing the crash report, it is still possible to find the crash report in a crash log file.
Minecraft launcher (Windows 8/10)
- Open File Explorer by clicking the folder icon or opening any folder.
- Click «This PC» in the left sidebar.
- Open the disk marked as C: .
- Open the Users folder.
- Find the folder named after your Windows account, and open it.
- At the top, click the «View» tab.
- Tick the checkbox next to «Hidden items». If you can’t see this, make the window bigger.
- Open the AppData folder.
- Open the Roaming folder.
- Open the .minecraft folder.
- Look for a crash-reports folder, and open it.
- Open the most recent file in this folder in a text editor of choice.
Technic launcher (Windows 8/10)
- Open File Explorer by clicking the folder icon or opening any folder.
- Click «This PC» in the left sidebar.
- Open the disk marked as C: .
- Open the Users folder.
- Find the folder named after your Windows account, and open it.
- At the top, click the «View» tab.
- Tick the checkbox next to «Hidden items». If you can’t see this, make the window bigger.
- Open the AppData folder.
- Open the Roaming folder.
- Open the .technic folder.
- Open the modpacks folder.
- Open the folder with your modpack name
- Look for a crash-reports folder, and open it.
- Open the most recent file in this folder in a text editor of choice.
AT launcher (Windows 8/10)
- In the AT launcher, click the «Open Folder» button at the bottom right.
- Open the instances folder.
- Open the PixelmonReforged folder.
- Look for a crash-reports folder, and open it.
- Open the most recent file in this folder in a text editor of choice.
Crash reports
Version 5.0-5.1
- «java.lang.OutOfMemoryError: Java heap space»
- «net.minecraftforge.fml.common.LoaderException: java.lang.OutOfMemoryError: Java heap space»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/. «
- «SplashProgress has detected a error loading Minecraft.»
- «Caused by: java.lang.IllegalAccessError: tried to access field net.minecraft.client.renderer.entity.RenderManager.field_178636_l from class com.pixelmonmod.pixelmon.client.ClientProxy»
- «at net.minecraft.world.World.getSkyColorBody(World.java:1477)»
You haven’t allocated enough memory to Minecraft. See Fixing memory issues for instructions about how to solve this issue.
- «Caused by: java.lang.NoSuchMethodError: com.pixelmonmod.pixelmon.items.PixelmonItemBlock.func_77655_b(Ljava/lang/String;)Lnet/minecraft/item/ItemBlock;»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraft/init/SoundEvents»
- «Caused by: java.lang.NoClassDefFoundError: net/minecraftforge/fml/common/event/FMLMissingMappingsEvent»
You need to use Minecraft 1.10.2 with this version of Pixelmon.
- «org.lwjgl.LWJGLException: Pixel format not accelerated»
Your graphics card is incompatible with Minecraft. There are several different causes and corresponding solutions to this issue; try this page.
- «java.lang.IllegalAccessError: tried to access field com.pixelmonmod.pixelmon.api.events.CaptureEvent.pokemon from class com.nguyenquyhy.PixelmonFriends.events.PixelmonEventHandler»
- «java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/api/enums/BattleResults»
You need to update Pixelmon Friends to the latest version.
- «java.lang.NoSuchFieldError: controlledPokemon»
You need to update Pixelmon TCG to the latest version.
- «java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/comm/packetHandlers/clientStorage/UpdateCurrency»
You need to update Economy Bridge to the latest version.
- «java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/items/ItemBlock»
You need to update Gameshark to the latest version.
- «Caused by: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/enums/EnumBattleType»
Gym Wars 2: Feebas Unleashed is currently incompatible with Pixelmon version 5.0.2+. Another Gym Plugin is an alternative Gym plugin that is compatible with the latest Pixelmon version.
Version 4.2-4.3
- «java.lang.OutOfMemoryError: Java heap space»
- «net.minecraft.client.renderer.StitcherException: Unable to fit: missingno — size: 16×16 — Maybe try a lowerresolution resourcepack?»
- «net.minecraftforge.fml.common.LoaderException: java.lang.OutOfMemoryError: Java heap space»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/. «
- «net.minecraftforge.fml.client.SplashProgress$5: java.lang.IllegalStateException: Splash thread»
- «SplashProgress has detected a error loading Minecraft.»
You haven’t allocated enough memory to Minecraft. See Fixing memory issues for instructions about how to solve this issue.
- «net.minecraftforge.fml.common.LoaderException: java.lang.ClassNotFoundException: com.pixelmonmod.pixelmon.Pixelmon»
You need to update your Java version to Java 8.
- «org.lwjgl.LWJGLException: Pixel format not accelerated»
Your graphics card is incompatible with Minecraft. There are several different causes and corresponding solutions to this issue; try this page.
- «net.minecraftforge.fml.common.LoaderException: java.lang.IllegalAccessError: tried to access field net.minecraft.client.renderer.entity.RenderManager.field_178636_l from class com.pixelmonmod.pixelmon.client.ClientProxy»
Make sure you did not extract or unzip the contents of the Pixelmon JAR; place the entire JAR into the mods folder. If you have already done this correctly, check if your Pixelmon JAR’s extension is .jar.zip ; if so, change the extension to .jar . If you do not see the .zip extension, you may need to have extensions showing on your system; a tutorial on how to do so can be found here.
- «java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/items/ItemBlock»
Gameshark is incompatible with this version of Pixelmon. You will need to remove Gameshark until it is updated to be compatible.
Version 4.0-4.1
- «java.lang.OutOfMemoryError: Java heap space»
- «java.lang.OutOfMemoryError: GC overhead limit exceeded»
- «java.lang.OutOfMemoryError: Rendering Block Entity»
- «java.lang.IllegalStateException: Splash thread»
- «net.minecraftforge.fml.common.LoaderException: java.lang.OutOfMemoryError: Java heap space»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/. «
- «net.minecraftforge.fml.client.SplashProgress$5: java.lang.IllegalStateException: Splash thread»
- «net.minecraft.client.renderer.StitcherException»
You haven’t allocated enough memory to Minecraft. See Fixing memory issues for instructions about how to solve this issue.
- «Could not reserve enough space for. object heap»
See Fixing memory issues for instructions about how to solve this issue.
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraftforge/common/util/EnumHelper»
- «java.lang.NoClassDefFoundError: net/minecraftforge/client/model/ItemLayerModel»
Use the recommended Forge version listed on the Pixelmon downloads page.
- «net.minecraftforge.fml.common.WrongMinecraftVersionException: Wrong Minecraft version for pixelmon»
You need to use Minecraft version 1.8 to use Pixelmon.
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/entities/npcs/EntityTrainer»
Remove Trainer Commands from your Pixelmon launcher profile and re-add it.
- «org.lwjgl.LWJGLException: Pixel format not accelerated»
Your graphics card is incompatible with Minecraft. There are several different causes and corresponding solutions to this issue; try this page.
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraftforge/client/model/IModel»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraftforge/client/model/ModelLoader»
- «net.minecraftforge.fml.common.LoaderException: java.lang.NoSuchMethodError: net.minecraftforge.client.model.ModelLoader.setCustomStateMapper(Lnet/minecraft/block/Block;Lnet/minecraft/client/renderer/block/statemap/IStateMapper;)V»
- «java.lang.NoClassDefFoundError: net/minecraftforge/common/util/EnumHelper»
Use the recommended Forge version listed on the Pixelmon downloads page.
- «java.lang.NoClassDefFoundError: cpw/mods/fml/relauncher/IFMLLoadingPlugin»
Don’t use Minecraft 1.7.10 mods with Minecraft 1.8.
- «java.lang.RuntimeException: org.lwjgl.LWJGLException: Could not create context (WGL_ARB_create_context)»
Open the splash.properties file in the config folder and disable the Forge splash screen.
- «net.minecraftforge.fml.common.LoaderException: java.lang.ClassNotFoundException: com.pixelmonmod.pixelmon.Pixelmon»
Don’t extract or unzip the Pixelmon JAR. Place the JAR itself in the mods folder instead.
- «net.minecraftforge.fml.common.LoaderException: java.lang.IllegalAccessError: tried to access field net.minecraft.client.renderer.entity.RenderManager.field_178636_l from class com.pixelmonmod.pixelmon.client.ClientProxy»
- «java.lang.IllegalAccessError: tried to access field net.minecraft.entity.projectile.EntityFishHook.field_146055_aB from class com.pixelmonmod.pixelmon.entities.projectiles.EntityHook»
If you are using Windows, rename the Pixelmon JAR from .jar.zip to .jar . If you do not see the .zip extension, you need to have extensions showing on your system; a tutorial on how to do so can be found here.
If you are using macOS, do not unzip the Pixelmon JAR. Place the JAR itself in the mods folder instead.
Version 3.5
- «at java.nio.Buffer.checkIndex(Buffer.java:540)»
- «at java.nio.DirectIntBufferU.get(Unknown Source)»
Lower your render distance to 16 chunks or less.
- «cpw.mods.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraftforge/event/world/BlockEvent$PlaceEvent»
Use the Forge version recommended on the Pixelmon downloads page.
- «java.lang.OutOfMemoryError: Java heap space»
- «java.lang.OutOfMemoryError: Initializing game»
- «net.minecraft.client.renderer.StitcherException: Unable to fit: missingno — size: 16×16 — Maybe try a lowerresolution resourcepack?»
You haven’t allocated enough memory to Minecraft. See Fixing memory issues for instructions about how to solve this issue.
Other problems
This section contains a few error messages that do not cause Minecraft to crash, but cause other problems when using Pixelmon.
- «Mod rejections [FMLMod:Pixelmon<x.x.x>]»
This error occurs you try to join a server that is using a different version of Pixelmon than the one you have installed. You need to install the version of Pixelmon indicated by the error message ( x.x.x ) in order to join this server. If you think you already have this version installed, check the «Mods» list on Minecraft’s main menu to make sure.
How to Find and Read a Minecraft Server Crash Report
If you’re ever running a server and it crashes, server crash reports are your best tool in finding what caused the crash, and can help you and anyone else trying to fix your server. When a server crashes it will usually generate a crash report, which will contain all the information needed to find the cause of the crash as well as taking the steps to fix it.
If your server crashed and made a crash report, you’ll see a message like this in the console, where the name of the file will be the date and time the server crash occurred:
HOW TO FIND A CRASH REPORT
Multicraft:
- Login to your panel (https://mc.shockbyte.com/index.php?r=site/page&view=home), and then navigate to the “Server” tab, and select the server that is crashing.
- Click the “login” button to access the files. If this gives you an error, simply re-enter your Multicraft password into the empty password field.
- Click on the folder in your server files called “crash-reports”.
- Then click on the newest crash report to open it, by default the newest crash report will be the one at the bottom. This will download it to your computer.
FileZilla:
- Use FileZilla to access your server files by logging in. If you’re having issues with this, we have a guide on how to get started using FileZilla here.
- On the bottom right hand side file browser, locate the “crash-reports” folder, this will be at the bottom of your server file list by default.
- Locate the newest crash report, this will be the top file by default. You can open it in 1 of 2 ways:
- Double click the file to download it to your computer, where you can open it on your PC.
- Right-click the file and select “View/Edit” to instantly open it with your default text program.
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Crash Reports 101
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Note: This topic is not for you to post your crash reports. This is for you to understand and hopefully fix your crashes yourself. As a final options you should always post the crash to the mod responsible for the crash (the final section of the topic suggests what should be included). I will not be fixing your crashes
When playing minecraft, occasionally it will close unexpectedly and crash. The most common cause of this behaviour is due to mods (bugs in the game can also cause crashes). Many people will encounter a crash then instantly post on the last recent mod installed topic «This made my game crash». As a modder I cannot stress how annoying this behaviour is, especially when an answer can be obtained by this person by reading and understanding why it happened. Now I know that a great majority of people are not very technically minded, that’s ok. It is for these people I have made this post for.
I will try and keep technical jargon at a minimum and explain any that is unavoidable. Hopefully this post may take the burden of some modders who get bogged down with crash report posts so they can get back to doing what they love, creating mods for the community. Furthermore I will try and keep things a bit more light hearted as well as providing random «Brotips»
Why does Minecraft crash?
In my experience there are a couple of main reasons minecraft crashes
- Improper installation of a mod or API
- Incompatibilities between mods
- Some sort of bug in a mod
- Pre-existing bug in minecraft
There can be other «fringe» cases of crashes (eg faulty hardware or not enough RAM) but the above will cover 99% of crashes encountered.
Now I just want to say, please don’t «blame» anyone for a crash. If it is due to an error in the modder coding (eg 2 or 3) cut them some slack. Most modders are not professional coders, they make mods for fun. If it is due to 1 (i.e. you made a mistake) just take a breath and re-read the installation instructions for both the mod and any APIs (as well as the rest of this guide).
Minecraft didn’t crash, it only blackscreened. What Do I do?
I want to start with the TL;DR version black screen = crash .
Sometimes rather than coming up with a nice little crash report, Minecraft will just show a black screen (Possibly flashing up «Saving Chunks» first). This is also a crash, and you should follow Part 2 of this guide. Crashes are generally caused by either exceptions or errors. These may or may not be caught by Minecraft’s internal error logger. If the error logger does catch it, you will be displayed with the minecraft crash screen, if not just a black screen. There are ways to obtain the crash report as detailed in Part 2 below.
The META-INF folder
I just want to digress a bit to discuss what the META-INF folder is. Essentially all you need to know is this needs to be deleted if you want to mod minecraft. If you don’t really care why then feel free to move to the next section. If you are curious, read on.
A java jar file is just a zip file with an optional META-INF folder. Because jars are not just a collection of .class files and resources, extra information is sometimes required (or desired) by application developers. The META-INF folder is a place to store package and extension configuration data, including security, versioning, extension and services. In Minecraft the security is the reason it must be deleted. The META-INF contains a file called «MAJONG_C.SF». This file contains a little code for each file within the jar which can be used to check if any file has been modified or corrupted. Therefore this file must be deleted to prevent the security check if you want to edit any of the files within the jar.
Now this is a very basic description of the META-INF folder as I was trying to make it as easy to understand as possible. If you are still interested look up the .jar file documentation on the java website
Ok so you have identified that minecraft has crashed. How do we get the crash report?
Minecraft output
If you are lucky a nice screen would have popped up with the crash report right in front, if this is the case move on to Part 3.
The output should look something like this
The part you need is in the white box.If no crash is displayed on screen there are ways of obtaining the crash report, so use one of the methods detailed below.
Crash txt files
Both Modloader and Minecraft Forge try and output any crash reports into folders. This should be the 1st place to check. Now you do have to be carefully because occasionally I get people posting the contents of one of these files that doesn’t actually contain the crash log (i.e. not helpful). Don’t worry if this is the case, I will detail in Part 3 how to read the crash report meaning you will know if you have the wrong file. If this is the case, try another method described below.
Note: When I refer to directories in this section, everything is relative to the .minecraft directory. I will assume if you are installing mods you already know how to find it (It is dependent on your operating system)
BroTip: In windows the directory can be easily found by pressing the windows key + ‘R’ and typing «%AppData» (without the «‘s) in the run dialog and pressing Enter. This should bring up an explorer window withe the .minecraft directory somewhere near the top.
Modloader
Modloader generally tries to output it’s crash reports in a file called «Modloader.txt». The file should be located in the «.minecraft» directory. This will only be from the last run of minecraft (i.e overwritten on each run). This obviously will only be present if you have modloader installed (Minecraft Forge has a different way of reporting crashes).BroTip: If posting from the Modloader.txt file make sure it actually contains a crash, I couldn’t tell you how many times people post me the contents of their Modloader.txt file when there is no crash in there.
Minecraft Forge
There is a folder that Minecraft Forge creates devoted to crash logs. The folder is located in the .minecraft directory and is called «crash-reports». Each crash will display the date/time of the crash as well as the describing if the crash was in the client or server. Another thing that should be mentioned about this file is that it is set out differently to other crash logs. The Forge crash logs will have the stack trace at the top and the header information below it (they also contain a «witty» comment).BroTip: Try to avoid opening the forge crash logs with notepad on windows. Notepad does not recognise the newline character used (because it is quite crappy). Try opening it with wordpad instead (right click, go to open with and selected wordpad or «other programs» and find it).
Command Line
Now because you are hear I am going to assume you are not very technically minded, therefore using the command line may scare you a little. I want to start with, don’t be scared, the command line is a very powerful tool. Of course there are more «user friendly» ways, but the command line is quick and does not require downloading on any extra files. Now these do depend on your operating system so only read the relevant one below
Windows
- Open the command prompt by pressing windows key + ‘R’ and typing cmd in the run dialog (and press enter)
- Type «cd %AppData%» and press enter
- Type «cd .minecraft» and press enter
- Enter the following command
Note: for this to work you must have java as an environment variable. Read more here
OSX
Warning I do not have an Mac computer so I have not tested this and do not know how user friendly the method is. These instructions are from the Minecraft wiki page- Go to Macintosh HD/Applications/Utilities and open Console.app
- Run minecraft and when it crashes the java log will be added to the console, which you can then select and copy
Linux
- Open a terminal (on distributions such as Ubuntu/Linux Mint, this is done with Ctrl + Alt + T)
- Run
Note: Your current directory MUST be wherever the minecraft.jar file is. If you are using linux I am going to assume you know at least basic command line functions.
MC Patcher
MC Patcher can be a great tool for obtaining crash reports (personally I don’t like it for it’s HD patching capabilities because i don’t like it’s methods but that’s just me). Start by downloading mcpatcher from here
This is what the default interface should look like.
For this purpose I recommend unticking all boxes before proceeding and DO NOT hit patch. Hitting patch will make MCPatcher run through it’s patching routine, problem is this has been known to interfere with the proper running of some mods including Minecraft Forge. Pressing «Test Minecraft» (Red Arrow) will launch minecraft in offline mode. Recreate the crash. The output will be displayed in the «log» tab (Red arrow in the picture below)
Now the great thing about mcpatcher is that it actually tries to give you the deobscurificated class/method/field names in the crash report. This can be an unbelievable help to the author of the mod if you have found a new bug or incompatibility.
Bat script
Windows Only
I have also developed a bat script to assist in the gathering of crash logs. Unfortunately I found a bug in it. I will correct the bug and upload it at a later date.
Doing this could result in the modder (or others) politely telling you the problem, the modder not responding (they may be away or busy) or a very grumpy response (modder may have had a hard day and you are the 10th person posting the exact same report). In any case, most of the time by simply reading and understanding the error report you can solve the problem yourself much quicker and easier then posting and waiting for a response. Sometimes posting is unavoidable (maybe you found a new bug) but it really should be the last resort, not the first.
Now this section actually has a duel purpose, I am writing this both for users who receive crash reports to at least try and diagnose their problems but also for mod makes or just general good guys who are trying to help others with their crashes.
A crash report generally contains 2 main elements. Now these don’t really have formal names, but I generally refer to them as either the header or the stack trace. Also depending how you got the crash log there may also be other information that has been output that was likely left over mod debugging code, this can generally be ignored (although may be useful for the mod author).
Please note in this section I may interchange the word error and exception. There are important differences between these but I don’t think we really need to get bogged down by that right now.
Header
The header generally appears at the top of the crash report, it will generally contain things like your version of minecraft as well as the mods you have installed. Just a quick note on this, if you got your crash report from the forge «crash-reports» directory, the header will appear at the bottom and be set out slightly different. It will generally contain the same information just set out differently.
Here is an example of a header from someone who posted a crash report on my mod topic that uses Minecraft Forge.
Minecraft has stopped running because it encountered a problem; Unexpected error
This error has been saved to /Users/********/Library/Application Support/minecraft/crash-reports/crash-2012-09-24_10.39.53-client.txt for your convenience. Please include a copy of this file if you report this crash to anyone.— BEGIN ERROR REPORT e8848218 ———
Generated 9/24/12 10:39 AM— Minecraft Version: 1.3.2
— Operating System: Mac OS X (x86_64) version 10.7.4
— Java Version: 1.6.0_33, Apple Inc.
— Java VM Version: Java HotSpot™ 64-Bit Server VM (mixed mode), Apple Inc.
— Memory: 496632856 bytes (473 MB) / 534708224 bytes (509 MB) up to 1065025536 bytes (1015 MB)
— JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
— FML: FML v3.0.196.366 Minecraft Forge 4.1.1.251 4 mods loaded, 4 mods active
FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Core [Mine & Blade: Core] ([1.3.2] Mine & Blade — Core — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Armoury [Mine & Blade: Armoury] ([1.3.2] Mine & Blade — Armoury — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
— LWJGL: 2.4.2
— OpenGL: ATI Radeon HD 4670 OpenGL Engine GL version 2.1 ATI-7.18.18, ATI Technologies Inc.
— Is Modded: Definitely; ‘forge,fml’
— Type: Client
— Texture Pack: Default
— Profiler Position: N/A (disabled)Now right away from this we can see that this user is using the 1.3.2 version of minecraft, has minecraft forge installed, is using Mac OS X (64 bit) is using java 1.6, has 2 mods other than Minecraft Forge/FML both of which were loaded successfully (in this case they are both 2 parts of the same mod). Furthermore because the author (me) is so awesome and put the version of minecraft required in the zip name, we can tell that he is using a mod that is designed for the minecraft version he is using. So far everything looks great.
Brotip: If you are super worried about privacy and do not want to post your username, remove that section of the crash report or start it out like I did above.
The Modloader styled headers are slightly different, However I do not have access to one on hand right now (I only mod with forge) but they also generally show similar information. Crashes may occur without either modloader or forge (jar mods only or bugs in the vanilla game), again these should show the minecraft version/java version/os etc but for obvious reasons will not show loaded mods.
Stack Trace
The stacktrace is the main technical part of the crash log.
Here is an example (in this case it is the other half of the header posted in the above section)
Stack traces are always printed from most recent to the least recent step in the trace (kind of like your browser history is ordered from most recently visited sight to the site you viseted a long time ago). The first line will describe the type of error. Take note of this, it can help you diagnose most of the problems. In the example above this is
I will go into more detail about this error in the next section as it can be a common crash.
Brotip: When dealing with this remember «Google is your friend» googling the 1st part of the error «java.lang.NoClassDefFoundError» can help you diagnose the general cause quite easily. Going to the 4th result (which is the java documentation tells us that this means «Thrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found.». In other words something that minecraft or the mod thinks is there is not actually there. This could be improper installation or a corrupted file, but right away we know quite a bit about the error.
Under the error name is a whole heap of at (classname).(method). These can also be quite important to modders as it gives us a way to backtrack through the error to hopefully find the root of it. Again the most recent is at the top and least recent is at the bottom. This can be handy for those even without a background in programing. Sometimes you can find the culprit quite easily by scanning through the trace. For example if you see «mine_and_blade» in any part section, it is a good chance that the Mine & Blade mod is likely the source (In one way or another) of the crash.
For those who have a bit of programing experience what the above trace tells us is that the method a in ayq class had an error, it was called by the a method in the Minecraft class which was called by the next one down and so forth.
Now when we see a «Caused by» that means what we have is a «Chained Exception». This is important because it is often the case that one of the fundamental exceptions underlying the last encountered exception is the real culprit that must be appropriately addressed. So in other words, these secondary exceptions may be just as important. I can not tell you when they are and when they are not because it really depends on the particular error report.
So now we have the crash report and we have a very basic understanding of it, what now?
I thought I would start with a few common crashes that we might encounter. Again, if this can diagnose your problem we have saved you some time (you don’t have to wait for a response) and we are allowing modders to continue modding rather than diagnose and solve Evey error.
java.lang.NoClassDefFoundError: .
I wanted to start with the error I have been using in the examples above. Here is the full crash report
— BEGIN ERROR REPORT e8848218 ———
Generated 9/24/12 10:39 AM— Minecraft Version: 1.3.2
— Operating System: Mac OS X (x86_64) version 10.7.4
— Java Version: 1.6.0_33, Apple Inc.
— Java VM Version: Java HotSpot™ 64-Bit Server VM (mixed mode), Apple Inc.
— Memory: 496632856 bytes (473 MB) / 534708224 bytes (509 MB) up to 1065025536 bytes (1015 MB)
— JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
— FML: FML v3.0.196.366 Minecraft Forge 4.1.1.251 4 mods loaded, 4 mods active
FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Core [Mine & Blade: Core] ([1.3.2] Mine & Blade — Core — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Armoury [Mine & Blade: Armoury] ([1.3.2] Mine & Blade — Armoury — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
— LWJGL: 2.4.2
— OpenGL: ATI Radeon HD 4670 OpenGL Engine GL version 2.1 ATI-7.18.18, ATI Technologies Inc.
— Is Modded: Definitely; ‘forge,fml’
— Type: Client
— Texture Pack: Default
— Profiler Position: N/A (disabled)java.lang.NoClassDefFoundError: paulscode/sound/SoundSystem
at ayq.a(SoundManager.java:235)
at net.minecraft.client.Minecraft.a(Minecraft.java:1937)
at net.minecraft.client.Minecraft.a(Minecraft.java:1885)
at net.minecraft.client.Minecraft.a(Minecraft.java:1821)
at apq.e(SourceFile:142)
at apq.a(SourceFile:116)
at apn.a(SourceFile:64)
at apn.d(SourceFile:112)
at apn.m(SourceFile:100)
at net.minecraft.client.Minecraft.l(Minecraft.java:1482)
at net.minecraft.client.Minecraft.J(Minecraft.java:834)
at net.minecraft.client.Minecraft.run(Minecraft.java:764)
at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.ClassNotFoundException: paulscode.sound.SoundSystem
at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:125)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
. 13 more
Caused by: java.lang.NullPointerException
at org.objectweb.asm.ClassReader.(Unknown Source)
at cpw.mods.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:27)
at cpw.mods.fml.relauncher.RelaunchClassLoader.runTransformers(RelaunchClassLoader.java:167)
at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:118)
. 15 more
— END ERROR REPORT 99c3d4f5 ———-A NoClassDefFoundError is thrown whenever a java program can’t find a particular class that it thinks should be there. The class will be displayed after the ‘:’ as well as the package/folder it is contained in. In the example above that means that the class that cannot be found is called SoundSystem and it is located in the paulscode/sound package.
There are 3 main reasons this can occur listed below
- You have not installed a required dependency. This is probably the most common cause of this error. Most of the time you can guess the missed dependency by looking at the classname/package. One common one I have encountered is when people forget to install PlayerAPI. In this case the crash will display java.lang.NoClassDefFoundError: PlayerBase. Always go back and make sure you have installed all dependencies for a mod
- The next most common reason I have seen for this error is due to a corrupted file. This happens occasionally while downloading mods. Just try and re-download the mod or API and try again.
- The mod auther has not packaged a particular class file. This will generally mean that part of name/package will have something to do with the mod. Now this is more rare than the other 2 above because if a modder does make a mistake such as this they will generally address it quite quickly. Also remember that your 1st assumption should be a corrupt download (2 above) so try to re-download the mod 1st.
Now the error posted above was actually due to a corrupted download of Minecraft Forge. After the user re-downloaded Forge everything worked again.
java.lang.NullPointerException: .
The dreaded null pointer exception. The most common cause of this doosy is due to modder error. It can also be caused by incompatible mods or knock on effects from other errors but generally its because of dodgy code. Null pointer exceptions occur when java tried to access an empty object. Because the object doesn’t actually exist, java will have a cry and break down. Mostly this can’t be fixed by anyone other than the author of the mod(s) in question.
The only recommendations I can say for this is to
- Try and work out the mod causing the error by looking at the stack trace.
- Make sure you don’t have mods that are known to be incompatible installed
- Check the forum page to see if anyone else has already posted this error, if so there may already be a solution in the works and there is little point in re-posting the same error (maybe just a «I got the same error as x») but there is really no point in posting the exact same error log
Sorry I don’t have an example right now, but these errors can be quite varied. If anyone really wants one I will find one later (or generate one myself) and post it.
Block ID conflict
This happens when you install a mod that is trying to use the same block ID as another mod. They can be identified by the first error being java.lang.IllegalArgumentException: Slot xxx, where xxx is a number.
Here is an example
5 mods loaded
Minecraft Forge 3.2.5.120
FML v2.2.17.117
Forge Mod Loader version 2.2.17.117 for Minecraft 1.2.5
mod_MinecraftForge : Initialized (minecraft.jar)
mod_JammyFurniture : Initialized (1.2.5_Jammy_Furniture_Mod_Client_V3.6.zip)
Mine & Blade: Battlegear — 2.7.7.1 : Pre-initialized ([1.2.5] Mine & Blade Battlegear — 2.7.7.1.zip)
mod_UpdateManager : Pre-initialized ([1.2.5] Mine & Blade Battlegear — 2.7.7.1.zip)
mod_Armor : Pre-initialized (ArmorStand.zip)Minecraft has crashed!
———————-
Minecraft has stopped running because it encountered a problem.— BEGIN ERROR REPORT 96fc7838 ———
Generated 12/06/12 1:46 AM
Minecraft: Minecraft 1.2.5
OS: Windows 7 (amd64) version 6.1
Java: 1.7.0_04, Oracle Corporation
VM: Java HotSpot™ 64-Bit Server VM (mixed mode), Oracle Corporation
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 5570 version 4.2.11631 Compatibility Profile Context, ATI Technologies Inc.
java.lang.IllegalArgumentException: Slot 211 is already occupied by [email protected] when adding [email protected]
at pb.(Block.java:249)
at pb.(Block.java:281)
at agy.(BlockContainer.java:13)
at mine_and_blade.heraldry.BlockBanner.(BlockBanner.java:29)
at mine_and_blade.heraldry.BlockBanner_Forge.(BlockBanner_Forge.java:9)
at mine_and_blade.heraldry.HeraldryForgeInitialiser.initlaliseBanner(HeraldryForgeInitialiser.java:16)
at mod_MineAndBlade.load(mod_MineAndBlade.java:356)
at cpw.mods.fml.common.modloader.ModLoaderModContainer.init(ModLoaderModContainer.java:319)
at cpw.mods.fml.common.Loader.modInit(Loader.java:262)
at cpw.mods.fml.common.Loader.initializeMods(Loader.java:591)
at cpw.mods.fml.client.FMLClientHandler.onLoadComplete(FMLClientHandler.java:229)
at net.minecraft.client.Minecraft.a(Minecraft.java:426)
at net.minecraft.client.Minecraft.run(Minecraft.java:735)
at java.lang.Thread.run(Unknown Source)
— END ERROR REPORT 4721735d ———-These are generally easy to fix, most mods have some sort of config file (generally in the config directory of the .minecraft folder) that is generated the first time a mod is loaded. A mod can customise the block/item ids used in this file. So your best bet is to find the offending block id and change it in one of the mods and try again. You may have to try a number of times to find free block ids. Also minecraft does have a limited number of block IDs available for vanilla/modloader the limit is 255 (the 1st
150 or so are taken up by normal blocks) while Forge has increased this to a bit over 4000. I believe vanilla will increase this to 4000 but I don’t think it is currently implemented.
Just a note, conflicting Item ids will not cause a crash, but these can be identified by items randomly changing to another item on startup/crafting.
Brotip 1: A tool such as TMI can be used to help identify free block ids. The TMI side bar interface displays the block id used by whichever block you are overing over.
Brotip 2: If you can help it, always change the block ID of the most recently installed mod. Blocks in your world will also change.Checklist
I thought I would start with a basic checklist about posting crash reports.
- Obtain the crash report
- Make sure it is actually a crash report (i.e. has a java stack trace)
- Do basic diagnostics yourself (read the thread)
- Make sure it is not one of the common crashes seen here
- Identify the mod causing the error
- Try the mod on a fresh jar with only the required APIs, this will help determine if the problem is caused by an incompatability.
- Read the Troubleshooting/FAQ section of the Mod page to make sure it is not a common problem that can be fixed
- Read the known bugs on the Mod page to make sure your are not-reposting a known bug
- Read the Incompatible mods section to make sure that you are not using incompatible mods
- Read the last page or two to make sure someone hasn’t recently posted the same report (no point in reposting unless you have more information to add)
- Do a quick search on the forum topic using the most recent error (eg java.lang.NoClassDefFoundError: paulscode/sound/SoundSystem) as someone else may have already posted the same error a while ago and it has since been solved.
- Post your error using the guidelines below.
Always remember that posting the error should generally be your last resort. You will generally solve the problem quicker yourself as a modder is not always online to answer questions. You may not get a response for a few days and you can’t blame the modder for this. It is therefore in your best interest to at least try and solve it yourself.
Posting Guidelines
Now before I start, if a modder has another way they like to describe an error report follow theirs. This is just a suggestion.
When posting an crash report having as much detail as possible is the key. If you write stuff that’s not needed, who cares? But not having enough detail can be very annoying for those trying to help.
At minimum you want
- The crash report (the most important part)
- A detailed description of your problem (when did it crash, what were you doing in game etc). Again the more details the better, even if you don’t think they are relevant. Better to be safe then missing an important detail.
- A list of mods APIs and patches used, sometimes this may not be needed as the might be displayed in the crash log, however sometimes not all are displayed. This includes APIs such as Minecraft Forge & PlayerAPI as well as patches like McPatcher or jarmods like Optifine.
- Generally the OS that you use is not needed, java is generally cross platform. Although some mods may not like some OS because of the way certain features are written. Use your best judgement on this (especially considering it may already be in the crash report).
- Any other mod specific information that might be required. This one really depends on the mod you are using and will mainly apply to very special cases\
- Be Polite, as a modder I am much more likely to be more helpful to someone who has both been polite and actually tried to do a little homework (i.e stuff on this post) then to someone who as not.
Brotip: Crash logs can be quite long. Always put them in a spoiler as this will tidy up the post a bit. A spoiler can be made like this
If you do do this it might also be a good idea to also write what the crash was somewhere outside of the spoiler so it can be search for by other users easily.
An example post might look something like this
My minecraft crashed on startup with a java.lang.NoClassDefFoundError: paulscode/sound/SoundSystem.
I was using no other mods or APIs (other than those required by this mod) at the time. When I installed the APIs I used a fresh jar.
here is the crash report
— BEGIN ERROR REPORT e8848218 ———
Generated 9/24/12 10:39 AM— Minecraft Version: 1.3.2
— Operating System: Mac OS X (x86_64) version 10.7.4
— Java Version: 1.6.0_33, Apple Inc.
— Java VM Version: Java HotSpot™ 64-Bit Server VM (mixed mode), Apple Inc.
— Memory: 496632856 bytes (473 MB) / 534708224 bytes (509 MB) up to 1065025536 bytes (1015 MB)
— JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
— FML: FML v3.0.196.366 Minecraft Forge 4.1.1.251 4 mods loaded, 4 mods active
FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Core [Mine & Blade: Core] ([1.3.2] Mine & Blade — Core — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
MB_Armoury [Mine & Blade: Armoury] ([1.3.2] Mine & Blade — Armoury — Preview 1.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
— LWJGL: 2.4.2
— OpenGL: ATI Radeon HD 4670 OpenGL Engine GL version 2.1 ATI-7.18.18, ATI Technologies Inc.
— Is Modded: Definitely; ‘forge,fml’
— Type: Client
— Texture Pack: Default
— Profiler Position: N/A (disabled)java.lang.NoClassDefFoundError: paulscode/sound/SoundSystem
at ayq.a(SoundManager.java:235)
at net.minecraft.client.Minecraft.a(Minecraft.java:1937)
at net.minecraft.client.Minecraft.a(Minecraft.java:1885)
at net.minecraft.client.Minecraft.a(Minecraft.java:1821)
at apq.e(SourceFile:142)
at apq.a(SourceFile:116)
at apn.a(SourceFile:64)
at apn.d(SourceFile:112)
at apn.m(SourceFile:100)
at net.minecraft.client.Minecraft.l(Minecraft.java:1482)
at net.minecraft.client.Minecraft.J(Minecraft.java:834)
at net.minecraft.client.Minecraft.run(Minecraft.java:764)
at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.ClassNotFoundException: paulscode.sound.SoundSystem
at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:125)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
. 13 more
Caused by: java.lang.NullPointerException
at org.objectweb.asm.ClassReader.(Unknown Source)
at cpw.mods.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:27)
at cpw.mods.fml.relauncher.RelaunchClassLoader.runTransformers(RelaunchClassLoader.java:167)
at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:118)
. 15 more
— END ERROR REPORT 99c3d4f5 ———-The above is clear and concise and provides all required information.
Thank-you for reading this post. I hope this will help out anyone with crashes in the future. Also feel free to post links to this topic to anyone who requires it.
If you have any suggestions to add to it or to clean up anything please let me know.
HOW TO READ A CRASH REPORT
A typical crash report will look like the following:
The quickest way to find the cause of a crash report is to look at the “Description:” part of the report. This will often describe what caused the crash. If you are having issues understanding what the description means, then you can always copy and paste it into google, as this will often bring up pages where other people are having the same issue as you. Despite this, there are some common errors that you could have on your crash report:
Ticking Entity — This most likely means that there is a corrupt entity in your world, this type of world corruption is most likely to be fixable without loosing the whole world (but is much easier to fix by generating a new world).
Ticking World — This most likely means that the entire world itself is corrupt, this is usually caused by changing your version of Minecraft (creating a new world should fix this).
There’s plenty of other crash reasons, and even more if you are running a modded server, so if you’re still having issues with your server feel free to submit a ticket so that our Technical Team can take a look at your crash report for you. When making a ticket we suggest uploading the crash report to a website such as pastebin, making it easier for us to read.
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