download newest l# loader from:
download edited config.xml here
(credits to ionic)
copy this config.xml in your new l# folder.
open LeagueSharp.Loader.exe, wait the blue circle to end
-> mark all assemblies (click on the first, hold shift, click on the last) -> rightclick on it, click on Update and Compile
then it should work
This is a direct copy and paste from reddit just because i'm too lazy so credits to hackwurst for the guide.