XF 1.2 1.2.0 incompatible with my theme


in memoriam 1991-2020
If your forum is well known you should have a test site that you test any upgrades. It's been stated in plenty of places that 1.2 shouldn't be used on a live site during beta. Especially one as large as this one.

Only thing you can do is Revert to a back up or switch to using the default theme while waiting. There is NO downgrade option.