Wednesday, June 27, 2018

Azure Active Directory Connect, High CPU Usage After June 2018 Patching

I did the latest Microsoft security updates for some servers, and was noticing my server running Azure Active Directory Connect for Office 365 was running at very high CPU.  I wasn't successful at restarting it from within the guest (or, wasn't patient enough, take your pick) and reset the VM.  The issue persisted.

My Microsoft.Identity.Health.AadSync.MonitoringAgent.Startup.exe was running at 99%.

Some research quickly tipped me off to the culprit.  ( .NET Framework 4.7.2 was the culprit.  Uninstalling the right KB depends on your OS.

  • Server 2008 R2 - "Microsoft .NET Framework 4.7.2"
  • Server 2012 - KB4054542
  • Server 2012 R2 - KB4054566
  • Server 2016 - KB4054590
I was dealing with Server 2016, so I uninstalled KB4054590, restarted, and the server seems fine.

I'll be sure to monitor the version history to see if when I go to patch next month, if Azure Active Directory Connect has been updated to address this.


  1. Now fixed by Microsoft, just install the last version of AADConnect :)

    1. I was a little surprised they didn't fix it at the start of the July patch cycle. Better late than never.