So the upgrade broke two installations.
One hosted with plenty of plugins running on a VPS server. I haven't tried disabling the plugins yet. Not terribly happy about that one.
One is a new docker image that I've hosted on a raspberry pi.
dokuwiki:
image: linuxserver/dokuwiki:arm32v7-latest
No great loss, and as it was barely configured and only had a couple of plugins and no real content yet, I issued:
mv plugins/ plugins-old
mkdir plugins
chown pi:docker plugins
And now I get a fancy new error.
DokuWiki Setup Error
Something unforseen has happened: Maximum action transitions reached
Any suggestions?