You may see the following error in EMC: “An error caused a change in the current set of domain controllers”. Get-DatabaseAvailabilityGroup shown below, is just one of the failing functions:
This is usually combined with a slow (laggy) EMC in general.
The problem can occur after having demoted Domain Controllers in your domain that EMC wants to talk to. Using Set-ADServerSettings has no effect on this problem.
To resolve the issue, simply delete the following file (the file has no extension):
C:\Users\<user>\AppData\Roaming\Microsoft\MMC\Exchange Management Console
Now your EMC is responsive again and will not show DC related errors.
Thanks to Søren Reisz for testing!