Hello. this issue is relevant for the latest version of VanillaFix. When I start the client, the message "Unexpected error has occurred" appears. not even a loading screen. for example: Project ozone 3 starts with this version, but Omnifactory does not. Probably this is due to incompatibilitiy
latest (1).log

do you have optifine?

if so, you might need to remove it

Read the pinned issues (#296 and #265)