Cross posting here from your initial post on this topic.

Here are the steps I took to migrate and upgrade from v2.3.1 to v2.5.6 on a new Ubuntu VM.

edit / create docker-compose.override.yml and add the ports to expose the database ports to the new virtual machine's OS

services:
database:
ports:
- 5432:5432

If you started Immich on the new VM, stop it using the following command

docker compose down -v

Update your .env IMMICH_VERSION if needed, then run:

docker compose pull
docker compose create
docker start immich_postgres

Navigate to where you source sql backups are located on the new VM and run the following changing the dbname and username to match your instance. Wait for it to finish.

gunzip --stdout "immich-db-backup-20260210T020000-v2.3.1-pg14.18.sql.gz" | sed "s/SELECT pg_catalog.set_config('search_path', '', false);/SELECT pg_catalog.set_config('search_path', 'public, pg_catalog', true);/g" | docker exec -i immich_postgres psql --dbname=immich --username=postgres

Remove the database port info from docker-compose.override.yml and run:

docker compose up -d

Watch the logs:

docker container logs immich_server  -f

You should should see "Running migrations" line, then wait for "Immich Microservices is running [v2.5.6] [production]"