My minecraft keeps crashing whenever i log into a online server, i have no idea why but i do indeed have the crash report.

[20:36:48] [Client thread/INFO]: Setting user: APoisonPotato93
[20:36:48] [Client thread/INFO]: (Session ID is token:f32c25b375584675aa0b0b1eaed7fe4b:29ed969693cd41bda6666aa49813b952)
[20:36:53] [Client thread/INFO]: LWJGL Version: 2.9.4
[20:36:54] [Client thread/INFO]: Reloading ResourceManager: Default
[20:36:54] [Sound Library Loader/INFO]: Starting up SoundSystem...
[20:36:54] [Thread-6/INFO]: Initializing LWJGL OpenAL
[20:36:54] [Thread-6/INFO]: (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
[20:36:55] [Thread-6/INFO]: OpenAL initialized.
[20:36:55] [Sound Library Loader/INFO]: Sound engine started
[20:37:01] [Client thread/INFO]: Created: 512x512 textures-atlas
[20:37:09] [Client thread/INFO]: Connecting to mc.sparkade.net, 25565
[20:37:13] [Client thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.IndexOutOfBoundsException: readerIndex(1) + length(83) exceeds writerIndex(6): UnpooledHeapByteBuf(ridx: 1, widx: 6, cap: 6)
    at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_25]
    at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_25]
    at g.a(SourceFile:61) [1.8.4.jar:?]
    at ave.av(SourceFile:880) [1.8.4.jar:?]
    at ave.a(SourceFile:325) [1.8.4.jar:?]
    at net.minecraft.client.main.Main.main(SourceFile:124) [1.8.4.jar:?]
Caused by: java.lang.IndexOutOfBoundsException: readerIndex(1) + length(83) exceeds writerIndex(6): UnpooledHeapByteBuf(ridx: 1, widx: 6, cap: 6)
    at io.netty.buffer.AbstractByteBuf.checkReadableBytes(AbstractByteBuf.java:1175) ~[netty-all-4.0.23.Final.jar:4.0.23.Final]
    at io.netty.buffer.AbstractByteBuf.readBytes(AbstractByteBuf.java:655) ~[netty-all-4.0.23.Final.jar:4.0.23.Final]
    at em.readBytes(SourceFile:669) ~[1.8.4.jar:?]
    at em.c(SourceFile:243) ~[1.8.4.jar:?]
    at bcy.a(SourceFile:1291) ~[1.8.4.jar:?]
    at gg.a(SourceFile:52) ~[1.8.4.jar:?]
    at gg.a(SourceFile:9) ~[1.8.4.jar:?]
    at fh$1.run(SourceFile:13) ~[1.8.4.jar:?]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_25]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_25]
    at g.a(SourceFile:60) ~[1.8.4.jar:?]
    ... 3 more
[20:37:13] [Client thread/INFO]: [CHAT] You have no new mail.

Now, if anyone could help me fix this, it would be much appreciated! Cheers.

  • Is your mine craft up to date? And does this happen with all servers? May 21, 2015 at 0:47
  • Ya it happens with all of them, and yes it is updated to the latest version. I was playing on it then it just stopped worked, crashed and now it wont work. im going to try it on single player right now. May 21, 2015 at 0:58
  • How about your java? Check that is up to date. May 21, 2015 at 0:59
  • How do i do that? I'm not familiar with Java. =/ May 21, 2015 at 1:02
  • Link: java.com/en/download Just download it and launch it to update May 21, 2015 at 1:16

3 Answers 3


You should try reinstalling your Minecraft

Make sure you copy out the saves folder first, then remove the entire.minecraft folder.

  • i will do that! May 27, 2015 at 23:58
  • 1
    @jacobtohahn I can't help but notice, but you should clean up (edit) some of your previous posts as they're poorly written. Also, avoid posting multiple answers. Instead, edit your previous answer.
    – aytimothy
    May 28, 2015 at 1:20

As far as I see, it crashes when writing to a file(probably auto-saves). You either have an corrupted save directory or it's read-only or inaccessible or something like that.


I have just uninstalled Minecraft then re-installed it. It does indeed work now. I don't know why I didn't do this before i came on here and asked for help. Regardless, thank you for your help guys. :)

  • If the suggestion to reinstall is what helped you, you should vote up and acccept that answer.
    – WildWeazel
    Aug 20, 2015 at 18:21

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