I'm pretty sure the problem is that my jar file is missing and I only have the json file. I tried reinstalling and it just gives me the json file. the error is vague. just "it looks like an unexpected issue occurred. we are sorry for etc

 

edit: it may be optifine, lemme see

edit 2:it was optifine

Edited June 12, 20196 yr by eevee73

Optifine is pretty specific about the versions of forge it is compatible with, checking optifine's changelog will usually tell what forge build it works with.