Forge crashing on 1.9

[Echothefemale]

Minecraft forge for 1.9 keeps crashing as soon as i click "play" it either says:

Failed to download file, the file contents differ from what was expected.
Name: jopt-simple-4.6.jar
URL: https://libraries.minecraft.net/net/sf/jopt-simple/jopt-simple/4.6/jopt-simple-4.6.jar
Filename on disk: jopt-simple-4.6.jar
Path: C:\Users\Echo\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar
Exists: File

or "minecraft launcher has stopped working"....

any way to fix this?