Hi @MrGeneration, still some additional comments, because I wonder, if anyone at Zammad has ever fully done a database migration on CentOS 7 according to https://docs.zammad.org/en/latest/appendix/migrate-to-postgresql.html: The postgresql15 installation worked just fine on my side (in your installation some packages seem to be outdated), but some commands in the instructions have typos (it’s postgresql-14-setup initdb, not postgresql14-setup initdb, same with “15”, while up to “13” there was no dash yet, and the service name is postgresql-14, not postgresql14, again also for “15”).
But more important: pgloader doesn’t seem to be compatible with the scram-sha-256 password encryption method used since PG 13.5 (see [FEATURE] Add support for postgres scram-sha-256 authentication · Issue #1207 · dimitri/pgloader · GitHub). Anyone trying this method with a pristine PG installation will most probably fail. I finally followed these instructions to temporarily change the encryption method and now it seems to be working for me. But you might want to add a warning regarding this issue to the migration instructions.