A big oops

I told Forge to use the latest version (v.12), but have not yet opened any of my worlds for migration. However, all my game systems have yet to be updated to 12 and the system won’t let me load them (telling me that the system needs to be updated). So I tried setting the Game Manager to the latest stable release instead, but it still won’t let me in. Am I just hosed until the systems are updated?

Hey there. What systems do you use that you suspect may not be updated for V12? I know PF2e and 5e are both compatible with version 12.