Well, that purged 15 and installed 13, but strangely, same error. It aborted much closer to the beginning of the process. 
2025-11-01 15:30:26.522 UTC [2547] FATAL: database files are incompatible with server
2025-11-01 15:30:26.522 UTC [2547] DETAIL: The data directory was initialized by PostgreSQL version 15, which is not compatible with this versio
n 13.22 (Debian 13.22-1.pgdg12+1).
This is the point of failure:
Failed to migrate secondsite
#<StandardError:"An error has occurred, this and all later migrations canceled:\n\nERROR: must be owner of extension vector\n">
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/rack-mini-profiler-4.0.1/lib/patches/db/pg/alias_method.rb:109:in `exec'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/rack-mini-profiler-4.0.1/lib/patches/db/pg/alias_method.rb:109:in `async_exec'
I tried the 13 template. The problem is the database is already altered by 15 but the migration of the 2 added multi sites were somehow added with a user that seems to be unrecognized by the installer. Like I said above, there was no requirement for a user/password combo when I added these initially so I don’t know exactly how they got added to the data base.
Is there some value I can add to the user/password options that would satisfy them? Remember, I didn’t add them so what did the initial script put them in under if not postgres which seems to be the default user indicated by the output I see.
Would it be possible to just comment out the two added sites to get the database up and THEN maybe use whatever import method that is being used now?
This is a personal site mostly and losing it will be annoying but not devastating. I ‘stew_pid’ly thought my regular backups were getting this.