Every ten seconds my iMac is coming up with the following error
28/01/2016 10:29:48.563 com.apple.xpc.launchd[1]: (com.apple.mdworker.bundles[3926]) Could not find uid associated with service: 0: Undefined error: 0 504
28/01/2016 10:33:28.874 com.apple.xpc.launchd[1]: (com.apple.mdworker.bundles) Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Any idea what this means and how I can stop it?
There is no user with the ID 504 in my system that I can see hence very confused.