[2026-07-11 09:14:02 EDT] Mia R. (Customer): Hi, I’m running a self-hosted photo library on my home server and thumbnails stopped generating after I moved the library to a new drive.

[2026-07-11 09:14:27 EDT] Daniel (Support): Hi Mia, I can help with that. Which version are you running, and did the media path change during the move?

[2026-07-11 09:15:06 EDT] Mia R. (Customer): Version 1.12.4 in Docker. The old path was /mnt/photos and the new one is /media/storage/photos. I updated docker-compose.yml and the app can see the albums, but most thumbnails are gray placeholders.

[2026-07-11 09:15:48 EDT] Daniel (Support): Thanks. That usually means the database still has records, but the preview cache either points to old files or the worker can’t write new ones. Can you check whether the container has write access to the preview/cache folder?

[2026-07-11 09:16:33 EDT] Mia R. (Customer): The cache folder is mapped to ./cache:/app/cache. It exists, but I see a lot of permission denied messages in the logs.

[2026-07-11 09:17:05 EDT] Daniel (Support): That explains it. What user ID is the container running as?

[2026-07-11 09:17:41 EDT] Mia R. (Customer): PUID=1000 and PGID=1000.

[2026-07-11 09:18:14 EDT] Daniel (Support): Please run this on the host from the directory containing your compose file: sudo chown -R 1000:1000 ./cache. After that, restart the service and trigger a rescan.

[2026-07-11 09:19:52 EDT] Mia R. (Customer): Done. I restarted it. The logs look cleaner now, but thumbnails are still gray.

[2026-07-11 09:20:23 EDT] Daniel (Support): The existing failed preview jobs may need to be rebuilt. In the admin panel, go to Library > Maintenance and run “Regenerate thumbnails.” If you have a large library, start with “missing only.”

[2026-07-11 09:21:10 EDT] Mia R. (Customer): It’s about 84,000 photos. I clicked missing only and it says there are 61,438 queued.

[2026-07-11 09:21:46 EDT] Daniel (Support): That’s expected. You should see CPU usage increase and new files appear under the cache directory. It may take several hours depending on the server.

[2026-07-11 09:22:31 EDT] Mia R. (Customer): I’m seeing new .webp files now. Some albums are already showing previews again.

[2026-07-11 09:23:04 EDT] Daniel (Support): Good. One more thing: since you changed the media path, confirm your compose volume uses the same container-side path as before if possible. Changing only the host-side path avoids stale path references.

[2026-07-11 09:23:46 EDT] Mia R. (Customer): Ah, I changed both sides. It’s currently /media/storage/photos:/library.

[2026-07-11 09:24:18 EDT] Daniel (Support): That’s okay if the app is configured to use /library. If it previously used /photos internally, searches or old imports may behave oddly. Do you see the new path in Settings > Library?

[2026-07-11 09:24:59 EDT] Mia R. (Customer): It says /library now. I think I changed that yesterday.

[2026-07-11 09:25:22 EDT] Daniel (Support): Then you’re fine. Let the thumbnail job finish. If any items remain gray after completion, run a full rescan with “verify files” enabled.

[2026-07-11 09:26:03 EDT] Mia R. (Customer): Makes sense. The main issue was the cache permissions, then?

[2026-07-11 09:26:34 EDT] Daniel (Support): Yes. The app could read your photos but couldn’t write generated previews. Once ownership was fixed, the thumbnail worker started creating them again.

[2026-07-11 09:27:11 EDT] Mia R. (Customer): Great, thanks. I’ll let it run today.

[2026-07-11 09:27:25 EDT] Daniel (Support): You’re welcome. I’ll leave the ticket open for 24 hours in case the rebuild reports errors.