Before running pg_upgrade:

  • Both versions must be installed. New version’s cluster must be empty.

Power off both clusters:

_$: sudo systemctl stop postgresql@12-main.service
_$: sudo systemctl stop postgresql@14-main.service

Migrate your cluster (all databases) from version 12 to 14:

/usr/lib/postgresql/14/bin/pg_upgrade \
  --old-datadir /var/lib/postgresql/12/main \
  --new-datadir /var/lib/postgresql/14/main \
  --old-bindir /usr/lib/postgresql/12/bin \
  --new-bindir /usr/lib/postgresql/14/bin \
  --old-options ' -c config_file=/etc/postgresql/12/main/postgresql.conf' \
  --new-options ' -c config_file=/etc/postgresql/14/main/postgresql.conf'

Change the port to 5432 in the new cluster. Start the new cluster and check that everything is ok:

_$: sudo systemctl start postgresql@14-main.service

Delete the old cluster:

_$: sudo pg_dropcluster 12 main