Q:

I get a ConcurrentModificationException when attempting to launch Minecraft with Forge

I have tried to reinstall Minecraft with Forge multiple times, but Minecraft still won't launch.
When I check "Launcher Visibility" and change it to "Hide Launcher" and re-open, I get this error log in the console:
[13:20:11] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[13:20:11] [main/INFO] [LaunchWrapper]: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[13:20:11] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
[13:20:11] [main/INFO] [FML]: Forge Mod Loader version 7.10.18.1180 for Minecraft 1.7.10 loading
[13:20:11] [main/INFO] [FML]: Java is Java HotSpot(TM) 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
[13:20:11] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[13:20:11] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
[13:20:11] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[13:20:11] [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:?]

How can I resolve this?

A:

You are not using Forge 10.13.0.1180 as shown on this line
[13:20:11] [main/INFO] [FML]: Forge Mod Loader version 7.10.18.1180 for Minecraft 1.7.10 loading

What i would do is make a copy of your saves and then completely delete the .minecraft folder from appdata.
Reinstall minecraft completely from scratch and then 
Use this link to install the correct version of Forge.
It should work fine if you do this

