Alain Bourgeois <alain(dot)bourgeois(at)zetes(dot)com> writes:
> /usr/lib/systemd/system/postgresql-10.service has PGDATA=/var/lib/pgsql/10/data/, /var/lib/pgsql/10/data/postgtresql.conf holds data_directory = '/mnt/pgdata/pgdir'
This is probably the source of your problem. IIRC, pg_upgrade
needs to be pointed at the actual old data directory, not
PGDATA=/var/lib/pgsql/10/data.
regards, tom lane