2025/02/19 07:07:18 stdout 2025-02-19 06:07:15.744 UTC [53M] ERROR: init_memory_database(): Failed to attach disk database
2025/02/19 07:07:18 stdout 2025-02-19 06:07:15.742 UTC [53M] ERROR: Aliasclients table not initialized, database not available
2025/02/19 07:07:18 stdout 2025-02-19 06:07:15.742 UTC [53M] ERROR: create_aliasclients_table() failed!
2025/02/19 07:07:18 stdout 2025-02-19 06:07:15.742 UTC [53M] ERROR: ERROR: SQL query "CREATE TABLE aliasclient (id INTEGER PRIMARY KEY NOT NULL, name TEXT NOT NULL, comment TEXT);" failed: SQL logic error (SQLITE_ERROR)
2025/02/19 07:07:18 stdout 2025-02-19 06:07:15.742 UTC [53M] ERROR: SQLite3: table aliasclient already exists in "CREATE TABLE aliasclient (id INTEGER PRIMARY KEY NOT NULL, name TEXT NOT NULL, comment TEXT);" (1)
The exception to this is environment variables. You can start the container with the old variables in place but don’t expect them to work! It is recommended to read the docker section of our docs page before upgrading.
as well as the disclaimer for Pi-hole v6 Docker image:
!!! THE LATEST VERSION CONTAINS BREAKING CHANGES
Pi-hole v6 has been entirely redesigned from the ground up and contains many breaking changes.
Environment variable names have changed, script locations may have changed.
If you are using volumes to persist your configuration, be careful.
Replacing any v5 image (2024.07.0 and earlier) with a v6 image will result in updated configuration files. These changes are irreversible.
WEB_PORT was meant to pass a value to lighttpd's configuration in the container, in the case you ran a container where you can't have Docker map ports.
Pi-hole v6 doesn't use lighttpd anymore.
Depending on your Pi-hole container's Docker network mode, you can either map the port in your docker-compose or docker run script, or you tell Pi-hole's embedded webserver to bind a different port by setting FTLCONF_webserver_port.
aliasclients has nothing to do with Pi-hole's group management clients.
It's a somewhat experimental feature that would allow you to aggregate several client IPs under the same aliasclient name in Pi-hole's dashboard exclusively, see e.g. Aliasclient usage and queries - #5 by Bucking_Horn. It has no UI configuration component, other than enabling related debug information output (via debug.aliasclients).
Did you actively use that feature in v5, by manually inserting entries into the aliasclient table via SQL statements?