Unifi 5.6.22 Upgrade Fails to Start Linux ERROR system – [exec] error, rc=255

When upgrading Unifi to 5.6.22, you will find that Unifi does not start on Linux system.

If you see the log files, you will see something like this:


 <UniFi> ERROR system - [exec] error, rc=255

This is because of a change in the release notes:

The controller will not start if it is set to bind to a privileged port (<1024), as it now runs as a non-root user

To fix this, you must change your config file to use a port outside of the 1024 range. This will be an issue if you’ve changed your port, like me.

  1. Edit /var/lib/unifi/system.properties
  2. Change your ports from


  3. Now type
    sudo service unifi restart

You should now be able to login to your system using the new ports.

5 thoughts on “Unifi 5.6.22 Upgrade Fails to Start Linux ERROR system – [exec] error, rc=255”

  1. Any chance you could help me? I’m also getting a rc error=255 in my log but none of my ports are set below 1024 and I can’t access the web gui

    1. Sorry I didn’t see this earlier. If it’s not under 1024 you shouldn’t have an issue. Is this still the case?

  2. I have the same problem since upgrading to 5.10.19 (well, trying to anyhow). I have even tried a clean re-install, no luck. Is there a list of error codes available? A way to get more detailed error logs?

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