Minecraft Forge 1.8.9 jopt-simple-4.6.jar bug

I downloaded Minecraft forge 1.8.9 and when I load it up It crashes or says this

 
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: /home/test/.minecraft/libraries/net/sf/jopt-simple/jopt-simple/4.6/jopt-simple-4.6.jar
Exists: File

I think it's a problem with jopt-simple-4.6.jar but I have no idea how to fix it
also im on ubuntu 18.0.4
really need help