Troubleshooting

Thumbnails not showing / permission denied errors

Symptoms:

Cause:

PICR runs inside the container as UID 1000. If the cache folder on the host was created by Docker automatically (or by root), PICR cannot write thumbnails into it.

Fix:

Stop the container, fix ownership of the cache folder, then restart:

docker compose down
sudo chown -R 1000:1000 ./cache
docker compose up -d

Thumbnails will regenerate automatically once the container has write access.

Prevention:

Create the cache (and data) folders yourself before the very first docker compose up, as described in Installation. If you let Docker create them it will do so as root.

Thumbnails disappeared after restarting

If you deleted the cache folder and restarted, Docker will have recreated it as root — see the fix above.

The safe way to clear the thumbnail cache is to delete the contents of the folder, not the folder itself:

rm -rf ./cache/*

Can’t connect to the Postgres database

If PICR starts but immediately exits with a database connection error, the most common cause is another Postgres instance already using port 5432 on your host.

Both Synology DSM and DaVinci Resolve run their own Postgres servers on 5432 by default.

Fix — expose the container on a different host port in compose.yml:

db:
  ports:
    - '54321:5432'

This does not affect PICR itself (it connects to Postgres inside Docker using the internal port), but it frees up 5432 on the host for other tools.

PICR says database migrations failed on first start

PICR retries its startup migrations once after 10 seconds if Postgres is not ready yet. If it still fails, check:

  1. The db container is running and healthy (docker compose ps)
  2. Your compose.yml includes the healthcheck and depends_on.condition: service_healthy as shown in Installation
  3. The DATABASE_URL environment variable matches the credentials in the db service

Something else?

Check the GitHub Issues — search before opening a new one in case it has already been reported or resolved.