Written for Synergy 3 (v3.8.4), checked 20 October 2026.
Operating system: Windows, macOS, and Linux
What is the background service?
The background service is a special process (synergy-service) in Synergy 3 that runs the auto-discovery, config-sync, and many other functions. It communicates over your LAN (local area network) between all computers which Synergy 3 is installed on.
It is a separate process from the core daemon, which Synergy 3 uses on Windows to start the part that shares your keyboard and mouse.
Synergy 1 has no background service like this. On Windows it has only a daemon, which runs its core and which its settings call Use background service (daemon). For its Background service offline message, see: Messages and what to do
Saw Service cannot start while installing on Windows? See: Windows installation problem: Service cannot start
Send us a diagnostic report
If you see a background service error, please send us a diagnostic report from each computer. It tells us what went wrong so we can fix it. For the steps, see: Getting diagnostic info and logs
In the meantime, try the steps below.
Service version is out of date?
If Synergy 3 shows Service version is out of date., click Restart local background service in that message. If that doesn't help, restart the computer.
Complete reinstall
The most reliable way to fix most issues with the background service in Synergy 3 is a complete reinstall. Follow every step in order, including removing the settings files and restarting before you install again: Reinstalling or uninstalling
If that doesn't solve the problem, please continue reading.
macOS security settings
If you're using a Mac, there could be a problem with the macOS permissions Synergy 3 needs. Sometimes this fails silently and provides no information about an error. For the steps to fix it, see: Troubleshooting the macOS Device Control and Data Access or Accessibility permission
Run the reinstall commands
The synergy-service process comes with a built-in way of reinstalling itself: it sets itself up again and starts.
Windows
Start the Command Prompt app and run the following, which starts the background service again:
"C:\Program Files\Synergy\synergy-service.exe" -i
macOS
Start the Terminal app and run the following:
/Applications/Synergy.app/Contents/MacOS/synergy-service -u /Applications/Synergy.app/Contents/MacOS/synergy-service -i
Linux
Start the Terminal app and run the following. Both commands need sudo; you'll be asked for your password:
sudo /opt/Synergy/synergy-service -u sudo /opt/Synergy/synergy-service -i
Installed Synergy 3 from the Flatpak? Choose Exit from its tray icon, then open Synergy 3 again; it starts the background service as it opens.