Just upgraded my forum instance via the admin upgrade page, and when the upgrade finished, my site was unreachable (error 500).
The production log included lots of instances of “undefined method `client_overrides_exist?’”
I couldn’t see this method referenced from the code of any installed plugins so I assumed that maybe the upgrade had caused some inconsistency, and opted for a
./launcher rebuild app. This got the site working again. Very nervewracking, though
Just FYI in case anyone encounters the same.