Roon ARC stuck in synchronizing state for weeks despite connection reported as okay (ref#UJGMB9)

Support
1

Hi! What’s not quite right with Roon?

· Can’t reach my Server, remotes or ARC

Can’t connect to my Server, remotes or ARC

· Other ARC issues

Tell us what's going on

· Arc is syncronising since weeks. Never get the chance to use it. Roon says the connection is okay.

Tell us about your home network

· The port is 50002 The Server IP 192.168.178.10. The switch is a Silent Angel Bonn 8

2

Hello @Uli_Lennartz,

Thanks for reaching out.

If ARC has been stuck in a “Synchronizing” state for weeks, the most common cause is a corrupted or incomplete local ARC cache on the mobile device.

Please try the following first:

  1. Completely uninstall the Roon ARC app from your phone
  2. Reboot the phone
  3. Reinstall Roon ARC from the App Store / Play Store
  4. Open ARC and sign in again, allowing the initial sync to complete

This forces ARC to rebuild its local database from scratch and resolves the majority of cases where syncing never completes despite the connection reporting as OK.

If the issue persists after reinstalling, please let us know:

  • Which mobile device and OS version you’re using
  • Whether ARC is syncing over Wi-Fi or mobile data
  • Approximately how large your Roon library is

We’ll take it from there if needed.

3

Hi @Uli_Lennartz,

Thank you for your patience.

Reviewing this case, your Roon database is almost certainly too large to sync reliably with ARC.

Diagnostics show your library contains roughly 700,000 tracks. ARC isn’t built for full-scale library management like RoonServer, but it still needs to maintain the object graph for the entire database to track changes while offline. Syncing a library of this size would require transferring metadata, artwork, and track information for hundreds of thousands of objects in real time, which puts enormous strain on memory, network bandwidth, and processing. On top of that, Apple and Google impose limits on how much data any app can request on a phone, which makes this practically impossible.

To use ARC reliably, you’d need to rebuild your Roon database with a much smaller object count. Simply deleting or removing files won’t work, because Roon still retains the objects in its database. You’d need to start fresh and add only a portion of your library. In our testing, libraries of 100,000–200,000 tracks sync reliably on high-end phones.

We understand this is frustrating for users with large collections, but it’s a limitation imposed by the mobile platforms themselves, not by ARC.

Please let us know if we can answer any questions.

4

This thread will auto-close without any further responses after a few days, so please reach out if we can clarify any of the points in my response above. Thank you and we’ll happily answer any questions.