I am following the migration guide to move my mattermost server from one instance (u18.04+postgres10) to a new instance (u20.04+postgres13). Both installations are on the same server and schema version (5.36.1).
I am stuck on the DB migration part. I am using
pg_dumpall --user=postgres > mattermost_db on the old box and
psql -f mattermost_db mattermost on the new box but it fails with messages like:
psql:mattermost_db:40807: ERROR: relation "table_name" already exists, and
psql:mattermost_db:14: ERROR: role "mmuser" already exists
I know this is probably more of a postgres question than a mattermost question, but after a week of trying all sorts of things, I am really stuck.
Thank you so much in advance for any advice!