Minecraft Forums

Quote from DehFatMan»

Whenever I try to start my Forge, it will start launching then after 3 or so seconds, it will just stop and give me an error message (the whole launch log is down below). I have no Idea what to do, what the problem might be, I am just confused, this is one of the first times that forge hasn't worked for me and that happened when I updated my forge from 1.6.4 to 1.7.2. If anyone could help me out I would greatly appreciate it.

 
[19:01:40] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[19:01:40] [main/INFO] [LaunchWrapper]: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[19:01:40] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
[19:01:41] [main/INFO] [FML]: Forge Mod Loader version 7.2.211.1121 for Minecraft 1.7.2 loading
[19:01:41] [main/INFO] [FML]: Java is Java HotSpot(TM) Client VM, version 1.8.0_20, running on Windows 8:x86:6.2, installed at C:\Program Files (x86)\Java\jre1.8.0_20
[19:01:41] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[19:01:41] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
[19:01:41] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[19:01:41] [main/ERROR] [LaunchWrapper]: Unable to launch
java.util.ConcurrentModificationException
 at java.util.ArrayList$Itr.checkForComodification(Unknown Source) ~[?:1.8.0_20]
 at java.util.ArrayList$Itr.remove(Unknown Source) ~[?:1.8.0_20]
 at net.minecraft.launchwrapper.Launch.launch(Launch.java:117) [launchwrapper-1.9.jar:?]
 at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.9.jar:?]
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release