[Koha] Upgrade to 21.11 Fails

[Bruce A. Metcalf]

Greetings,

Yes, I'm slow on the uptake, I've been running oldoldstable for some 
time now. With the release of 22.11, it's time for me to move up.

My system was installed from deb packages under Debian 10, and has been 
updating fine.

After an update (with no error messages), I find I am unable to access 
either the OPAC or the admin interfaces. Both give an "Internal Server 
Error" message, with a note that a 500 error was thrown by the 
ErrorDocument handler as well.

Probably something simple, but not something I can see or find in the 
release notes. Help!

Regards,
/ Bruce /
Bruce A. Metcalf
Augustan Library