Minecraft Forums

Today, I installed Mapwriter for 1.7.2, and Forge for 1.7.2

I watched the log, and the button would go right back to "Play" instead of, "Already Playing"

I know this is a common issue.

I uninstalled Java 8 and installed Java 7, but it is still not working. Here are the logs:

[18:30:21] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[18:30:21] [main/INFO] [LaunchWrapper]: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[18:30:21] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
[18:30:21] [main/INFO] [FML]: Forge Mod Loader version 7.2.211.1121 for Minecraft 1.7.2 loading
[18:30:21] [main/INFO] [FML]: Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_25, running on Windows 8.1:amd64:6.3, installed at C:\Users\danny_000\Desktop\Everything\Games\runtime\jre-x64\1.8.0_25
[18:30:21] [main/WARN] [FML]: The coremod rangatangaa.minecraft.Blocks3D.B3DFMLLoadingPlugin does not have a MCVersion annotation, it may cause issues with this version of Minecraft
[18:30:21] [main/WARN] [FML]: The coremod invtweaks.forge.asm.FMLPlugin does not have a MCVersion annotation, it may cause issues with this version of Minecraft
[18:30:21] [main/INFO] [FML]: Loading tweaker optifine.OptiFineForgeTweaker from OptiFine_1.7.10_HD_A4.jar
[18:30:21] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[18:30:21] [main/INFO] [LaunchWrapper]: Loading tweak class name optifine.OptiFineForgeTweaker
[18:30:21] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
[18:30:21] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[18:30:21] [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:?]
Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

Thanks if you can help.