Today, I tried downloading the latest OptiFine file for 1.15.2 and tried getting it to run with Forge. However, I constantly ran into the error "_ is not a valid mod file". I downloaded Forge 31.2.20 through 31.2.24 and none of those versions could load OptiFine. On OptiFine's twitter, it said OptiFine pre30 was compatible with Forge 31.2.21, so I am confused as to why it is not working. I am not very tech savvy and have no idea how to fix this. Any help is appreciated.