Well it took me some time too look at it again, but yes finally I found the problem.
I think I have not done it properly in the first place as I have not imported the table before updating FOP2.
But I discovered some more problems e.g. regular segfaults on debian 12 and a few php8.2 (freepbx17)
deprecations with caused this error and others like plugins in the admin not showing up properly.
I put a modified / adapted version of fop2 on github.
It's split between webroot for php files and server/systemd
It' here : https://github.com/schiffsratte/fop2-modernize
