I have the same issue. pg_lsclusteres returns:
sudo pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
12 main 5432 online postgres /var/lib/postgresql/12/main /var/log/postgresql/postgresql-12-main.log
13 main 5433 online postgres /var/lib/postgresql/13/main /var/log/postgresql/postgresql-13-main.log
It is not possible to upgrade ‘main’ cluster to 13 since it already exists.
The error and fix provided in Step 5 of gvm-check-setup is either vague, incomplete, or incorrect:
Step 5: Checking Postgresql DB and user …
ERROR: The default postgresql version is not the one used for gvmd compilation: (12, need 13).
FIX: Please use pg_upgradecluster to upgrade your postgresql installation
It would be great to have a ‘FIX’ message that better described the actual fix.