ARC is no longer working. Summary below, created with Copilot.
Thank you. André.
Context
• Windows 11 fully updated • Roon freshly reinstalled • Database restored from a healthy backup • Local playback, RAAT, endpoints, and library all working normally • Only Roon ARC is not functioning
ARC Symptoms
• ARC shows “syncing for the first time…” indefinitely • ARC can see playlists, but they are outdated (no recent changes) • ARC remains stuck even after force closing the app • ARC settings are inaccessible during the sync • ARC never completes the initial synchronization
RoonServer Symptoms
• In Settings → Roon ARC: o Immediate error o The Test button instantly returns to the same error o No progress messages • Roon reports “Port 55000 already in use”, but: o The port is free o UPnP is working o No double NAT o No VPN o ARC was working before the recent update
Troubleshooting Already Performed
1. Full reinstall
• Uninstalled Roon • Deleted Roon and RoonServer folders in AppData • Rebooted • Reinstalled Roon • Restored backup → No change
2. Process cleanup
• Closed Roon • Killed processes: o Roon.exe o RoonAppliance.exe o RAATServer.exe o RoonServer.exe • Rebooted → No change
3. ARC reset on the phone
• Enabled offline mode • Disconnected from server • Reconnected → ARC enters “syncing for the first time…” but never finishes
4. ARC folder check
• Looked in: Code %localappdata%\RoonServer • No ARC folder present → Cannot force ARC rebuild manually
5. Network checks
• UPnP OK • No firewall blocking • No VPN • ARC can reach the server but cannot synchronize → Problem is not network related
Conclusion
Everything in Roon works normally except ARC. The server appears unable to rebuild the internal ARC module after the update/restore. ARC remains stuck in “syncing”, and the Test button fails instantly.
Request
I need assistance to: • Force a rebuild of the ARC module on the server side or • Provide a Windows installer that includes the legacy RoonServer service (if required for ARC to function)
Merci.
Tell us about your home network
· 3 PC Windows 11 - 1 - roon server, client, ethernet direct to orange box, 2 - client, wifi, 3 - client, wifi. Smartphone android, ARC.
Thanks for reaching out. Our diagnostics indicate that your Roon library is roughly ~170,000 tracks. Unfortunately, you’ll find that sync isn’t always reliable when attempting to pair ARC with a Roon database of this size. ARC performs reliably up to about ~100,000 tracks in its current implementation. Although engineering is working to expand tolerance above that, there are inevitable hard ceilings imposed by the operating system on this scale of data transfer.
Please try reinstalling the ARC app itself once more and attempting the initial sync again. Let us know if you see a different failure.
Another option here is to rebuild the library from scratch with a smaller total track count. Since the object count (not the storage volume) is the chokepoint for the OS and ARC framework during sync, simply deleting items out of the existing library won’t suffice. But recreating a new version of the database with under 100,000 tracks will relieve sync failures. Let us know if you want to proceed with this heavy-handed option and we can send instructions.
- Am I to understand that even though everything is working well now, it might deteriorate?
- Yes, of course; please let me know the steps to lighten the load.
- Actually, I’d like to keep all the tagged items. Focus is great for discovery, but I’m building a personal organization system; adding a composer or artist requires an album, and when you factor in external recommendations and thematic playlists of complete sequences, things get bloated.
If the size of the library grows and gets too large, then yes, the ARC sync can deteriorate in the future. To properly remove media from your library, please move it out of a Roon watched folder, and then you will need to run a Clean Up Library function. Note that Clean Up Library removes metadata associated with any inactive Roon watched location, so please ensure that all of your desired media is currently being seen by Roon before performing this function. For additional information, please see our guide on this:
