Written for Synergy 3 (v3.7.2) and Synergy 1 (v1.21.4), checked 3 October 2026.
Product: Synergy 1 and Synergy 3
Operating system: macOS
If macOS says it can't update Synergy 1 or Synergy 3 because the app is in use, quit it from its menu bar icon, then run the update again. Closing the window isn't enough: the app keeps running in the background.
How to fix it
- Click the Synergy 1 or Synergy 3 icon in the menu bar at the top of your screen.
- In Synergy 3, choose Exit. In Synergy 1, choose Quit.
- Run the update again.
If the message still appears, restart the Mac and run the update before opening Synergy 1 or Synergy 3 again.
Closing processes
If restarting doesn't clear it, open Activity Monitor (Applications, then Utilities, then Activity Monitor), search for synergy, and quit every process it finds. Or run this in Terminal:
pkill -i synergy
Synergy 3's background service can start again by itself after being force quit. If it does, use Exit from the menu bar icon, or remove the app as below.
Removing the .app
If that doesn't help either, remove the app from Terminal. Open Terminal (Applications, then Utilities, then Terminal) and run:
sudo rm -rf /Applications/Synergy.app/
This removes the app you see in the Applications folder. Once its processes have stopped or the app has been removed, continue with the update.