I uninstalled all extra extensions to make sure the upgrade runs through. Unfortunately it does not.
I tried to replace the /concrete directory and after this failed (and I restored the original filesystem without extensions and DB) I tried the internal upgrading process:
Both ways show up kind of the same error message: Sooner or later some column is missing from an SQL statement.
Also: The internal process shows up a “bad gateway” error on the server. Refreshing that page does not change anything (bad gateway again). Afterwards the missing column error occurs.
Currently I restored the original fileset and DB (without extensions) so I do not have the exact message to post here.
All ConcreteCMS caching is currently off.
PHP 7.4.30 and MySQL version: 8.0.20 are installed.
PHP memory limit: 512 MB,
PHP max execution time: 30s