I am running (3) applications on a Raspberry Pi server. I am upgrading the server to Buster. I copied the html directory to the new server. I installed the databases from backups and all looks OK. (2) of the applications came up fine. However Piwigo is failing with a general error. "This page isn’t working localhost is currently unable to handle this request. HTTP ERROR 500". A remote connect has the same error. It is running PHP 8.0.5. I searched the forum for other 500 errors and none seemed to help or fit.

Any ideas?