Oct 13, 2014 1:12:51 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker

Oct 13, 2014 1:12:52 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker

Oct 13, 2014 1:12:52 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker

2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading

2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Java is Java HotSpot 64-Bit Server VM, version 1.8.0_20, running on Windows 7:amd64:6.1, installed at C:\Program Files\Java\jre1.8.0_20

2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-10-13 13:12:52 [sEVERE] [ForgeModLoader] Unable to launch

java.util.ConcurrentModificationException

at java.util.ArrayList$Itr.checkForComodification(Unknown Source)

at java.util.ArrayList$Itr.remove(Unknown Source)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:114)

at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true

Java HotSpot 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

 

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This keeps on happening for every mod pack I run with even other versions of forge, I have looked for fixes on Google but it seems like not many people know how to answer this problem...

I found a semi-fix for this. I just downgraded Java 1.8.0_20 to Java 1.8.0_11. I found a post that was similar to mine and an admin replied that there's a bug with Java 1.8.0_20:

 

Here's the link: http://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase8-2177648.html#jre-8u11-oth-JPR

You don't actually have to downgrade. This issue has been fixed for at least a month - you just have to update to the latest forge version.

 

https://github.com/LexManos/LegacyJavaFixer

http://files.minecraftforge.net/LegacyJavaFixer/legacyjavafixer-1.0.jar

Its under the DONT FUCKING BOTHER ME JUST FUCKING USE IT license

{technically MIT but people never read that}