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Minecraft runs fine without forge, and forge said it had installed correctly. But if we try to run MC 1.7.2 or 1.6.4 with correct forge version MC shuts down completely and we get the following error message in the log file:



[11:03:54] [main/ERROR] [LaunchWrapper/]: Unable to launch
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) ~[?:1.8.0_25]
at java.util.ArrayList$Itr.remove(ArrayList.java:865) ~[?:1.8.0_25]
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:?]



The java version is up to date, and this happens even if I completely disable the firewall.



Any suggestions?

Quote from Tobias53»

Minecraft runs fine without forge, and forge said it had installed correctly. But if we try to run MC 1.7.2 or 1.6.4 with correct forge version MC shuts down completely and we get the following error message in the log file:



[11:03:54] [main/ERROR] [LaunchWrapper/]: Unable to launch
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) ~[?:1.8.0_25]
at java.util.ArrayList$Itr.remove(ArrayList.java:865) ~[?:1.8.0_25]
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:?]



The java version is up to date, and this happens even if I completely disable the firewall.



Any suggestions?

Install Legacy Java Fixer mod (place it in your mods folder).