pf@xxxxxxxxxxx writes: > Trying to upgrade from 13.6 to 15.1, pg_upgrade complains with: > [postgres@pf ~]$ /usr/bin/pg_upgrade -b /usr/local/pgsql/bin -B /usr/bin \ > -d /mnt/db/var/lib/pgsql/data -D /mnt/work/var/lib/pgsql/data \ > -s /tmp -U postgres > This utility can only upgrade to PostgreSQL version 15. <=====<<< ?? This indicates that it thinks the new data directory (-D) is the wrong version. Perhaps the error message could be clearer about that. > Due to the database size, I have the working copy on a 4TB NVMe SSD > mounted at /mnt/work/var/lib/{pgadmin,pgsql} and an identical copy on an > 18TB platter at /mnt/db/var/lib/{pgadmin,pgsql}. Both copies are > currently at 13.6. I think you misunderstand how this is supposed to work. The -D argument should point at an *empty* data directory that has been freshly initialized with the new version's initdb. pg_upgrade then transfers data into that from the old database (-d argument). regards, tom lane