[Nextcloud] duplicate key value violates unique constraint "fs_storage_path_hash"

Hey folks,
I migrated my database from MariaDB to PSQL this weekend using this command:

Versions

Backup = 1.0.6
Nextcloud Server = Nextcloud Hub II 23.0.0

DB Migration

docker exec -u <id www user>:<gid www user> -ti <containerID> php occ db:convert-type --all-apps --password="<db-pw>" pgsql nextcloud db-postgres nextcloud

This did not report any errors etc so I assume nextcloud migrated with success.

Error Picture

However, after the migration was done I encountered strange behavior, since nextcloud often switches to maintenance back and forth (almost minutewise). I looked up and saw in Postgres stuff like that:

docker-nextcloud-db-postgres-1  | 2022-06-22 04:03:44.235 UTC [381225] DETAIL:  Key (objecttype, objectid, systemtagid)=(files, 390134, 19) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:03:44.236 UTC [381225] DETAIL:  Key (objecttype, objectid, systemtagid)=(files, 390131, 153) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:03:44.237 UTC [381225] DETAIL:  Key (objecttype, objectid, systemtagid)=(files, 390107, 153) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:03:44.237 UTC [381225] DETAIL:  Key (objecttype, objectid, systemtagid)=(files, 390107, 37) already exists.
[...]

and this...

docker-nextcloud-db-postgres-1  | 2022-06-22 04:07:41.198 UTC [381226] ERROR:  duplicate key value violates unique constraint "fs_storage_path_hash"
docker-nextcloud-db-postgres-1  | 2022-06-22 04:07:41.198 UTC [381226] DETAIL:  Key (storage, path_hash)=(14, 2f5b76cbc822adadc9782549ce5258a7) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:07:41.198 UTC [381226] STATEMENT:  INSERT INTO "oc_filecache" ("mimepart", "mimetype", "mtime", "size", "etag", "storage_mtime", "permissions", "name", "parent", "checksum", "path_hash", "path", "storage") VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13)
docker-nextcloud-db-postgres-1  | 2022-06-22 04:08:58.225 UTC [381226] ERROR:  duplicate key value violates unique constraint "fs_storage_path_hash"
docker-nextcloud-db-postgres-1  | 2022-06-22 04:08:58.225 UTC [381226] DETAIL:  Key (storage, path_hash)=(14, 213cd3df74fcae566453aff6e878f7f2) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:08:58.225 UTC [381226] STATEMENT:  INSERT INTO "oc_filecache" ("mimepart", "mimetype", "mtime", "size", "etag", "storage_mtime", "permissions", "name", "parent", "checksum", "path_hash", "path", "storage") VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13)
docker-nextcloud-db-postgres-1  | 2022-06-22 04:09:19.657 UTC [381226] ERROR:  duplicate key value violates unique constraint "fs_storage_path_hash"
docker-nextcloud-db-postgres-1  | 2022-06-22 04:09:19.657 UTC [381226] DETAIL:  Key (storage, path_hash)=(14, 94ad1a9b370fcdc1b4bfdb427a89831f) already exists.
docker-nextcloud-db-postgres-1  | 2022-06-22 04:09:19.657 UTC [381226] STATEMENT:  INSERT INTO "oc_filecache" ("mimepart", "mimetype", "mtime", "size", "etag", "storage_mtime", "permissions", "name", "parent", "checksum", "path_hash", "path", "storage") VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13)
[...]

DB investigation

Running the following in Postgres gave me the clue that somethis is wrong with the backup app or at least with its database entries:

select * from oc_filecache where storage=14;

Which looks like this:

Reset

After Runnin the following command, the entities are still persistent within the database:

docker exec -u <id www user>:<gid www user> -ti <containerID> php occ backup:reset

I'd like to use the Backup app in the future so any help would be appreciated.

Start by reviewing the reported php occ db:convert-type migration and php occ backup:reset entry points, then inspect the oc_filecache rows and fs_storage_path_hash violations described in the logs. Reproduce the MariaDB-to-PostgreSQL migration if possible and determine why duplicate file-cache entries remain after reset. Done means the migration and reset no longer leave recurring unique-constraint errors.