Apple - What causes the UserEventAgent to run with 100% CPU usage?
Ive just solved this by disconnecting and reconnecting the power cable from Mac. The light was green, battery indicator on the screen was saying that the battery is charged but maybe there was power cable tip misalignment or something that caused this issue.
Same issue. I completely reinstalled 10.11.3 on an erased drive and the problem persists. This is an OS X bug so send Apple a bug report.
My temporary solution is to disable the launch daemon:
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.UserEventAgent-System.plist
But you must remember to load it prior to the next boot or in safe mode, or else many things will fail at the next boot.
Unfortunately, we must wait for Apple to get their act together on this one.
In my case it seemed to be the Wacom tablet driver.
Wacom has updated its driver to 6.3.15-2 RC. The changelog says:
- UserEventAgent hangs at or near 100% CPU usage at startup
I just updated to this driver, and it seems to work fine.
If the driver update does not help, deleting those files also fixed this problem for me:
/Library/LaunchAgents/com.wacom.wacomtablet.plist
/Library/LaunchDemons/com.wacom.displayhelper.plist