I was getting a sporadic error with SSO signon to the vCSA Web Client. The error was
"The authentication server returned an unexpected error: ns0:RequestFailed: Operations error. The error may be caused by a malfunctioning identity source."
When viewing users for the domain in the SSO configuration on the vCSA Web user interface, I would get this error.
"Error: Idm client exception: Operations error"
Another symptom of the issue was nslookup was pausing when returning the results of a “nslookup
Turns out, I had an incorrect forwarder set on my DC. The pause was a result of the DC timing out trying to reach the forwarder. Moral of the story, when you get these errors, validate your DNS is configured and functioning properly.