Please run
pihole checkout ftl v5.16.3
to get back to a working version until we have found a permanent solution to this. (edit: see below)
When you see an error like
please
edit We decided that supporting very old operating system releases (where there is at least one stable newer version) can be too much at times. You can run your Pi-hole completely fine pinned to this version until you decide to upgrade the underlying system. At some point you will have to, anyway. I'm sorry to say this but we're a small team and all are volunteers (as in: other jobs pay our daily bread) and it seems better to make such a decision rather than trying to fit in everywhere and possibly not doing it right.