So I tried to use Minecraft Forge for 1.6.4 and 1.7.2, but when I click launch on any of the forge profiles, this pops up:

 

(I think this is because the Minecraft servers are down A.T.M.)

 

Sep 23, 2014 7:44:18 PM net.minecraft.launchwrapper.LogWrapper log

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

Sep 23, 2014 7:44:18 PM net.minecraft.launchwrapper.LogWrapper log

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

Sep 23, 2014 7:44:18 PM net.minecraft.launchwrapper.LogWrapper log

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

2014-09-23 19:44:18 [iNFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading

2014-09-23 19:44:18 [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\jdk1.8.0_20\jre

2014-09-23 19:44:18 [WARNING] [ForgeModLoader] The coremod com.spacechase0.minecraft.spacecore.asm.SpaceCorePlugin does not have a MCVersion annotation, it may cause issues with this version of Minecraft

2014-09-23 19:44:18 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-09-23 19:44:18 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

2014-09-23 19:44:18 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-09-23 19:44:19 [sEVERE] [ForgeModLoader] Unable to launch

java.util.ConcurrentModificationException

at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)

at java.util.ArrayList$Itr.remove(ArrayList.java:865)

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

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

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

 

 

It'd be awesome if someone could tell me how to fix this!

 

EDIT: I also just re-installed Minecraft so I re-installed Minecraft Forge, this is the first time this problem has happend, and I haven't tweaked with the .jar or anything.

 

 

Here's the log (I don't know much about coding so I don't know which log is the most recent so I pasted the number 0 log) 2014-09-23 19:20:54 [iNFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading

2014-09-23 19:20:54 [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\jdk1.8.0_20\jre

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Java classpath at launch is C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\minecraftforge\minecraftforge\9.11.1.965\minecraftforge-9.11.1.965.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\minecraft\launchwrapper\1.8\launchwrapper-1.8.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\ow2\asm\asm-all\4.1\asm-all-4.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\scala-lang\scala-library\2.10.2\scala-library-2.10.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\scala-lang\scala-compiler\2.10.2\scala-compiler-2.10.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\lzma\lzma\0.0.1\lzma-0.0.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\argo\argo\2.25_fixed\argo-2.25_fixed.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4-Forge9.11.1.965\1.6.4-Forge9.11.1.965.jar

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Java library path at launch is C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4-Forge9.11.1.965\1.6.4-Forge9.11.1.965-natives-7997161452719

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Enabling runtime deobfuscation

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Instantiating coremod class FMLCorePlugin

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Enqueued coremod FMLCorePlugin

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Instantiating coremod class FMLForgePlugin

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Enqueued coremod FMLForgePlugin

2014-09-23 19:20:54 [FINE] [ForgeModLoader] All fundamental core mods are successfully located

2014-09-23 19:20:54 [FINE] [ForgeModLoader] Discovering coremods

2014-09-23 19:20:54 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-09-23 19:20:54 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

2014-09-23 19:20:54 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-09-23 19:20:54 [sEVERE] [ForgeModLoader] Unable to launch

java.util.ConcurrentModificationException

at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)

at java.util.ArrayList$Itr.remove(ArrayList.java:865)

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

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

 

 

Use the latest forge.

1.6.4 / 1.7.2 is no longer supported, update to 1.7.10 and use latest Forge build.

Read the EAQ.