On one of my Exchange 2010 nodes I randomly kept getting this error message whenever I executed simple tasks such as "Looking up email properties for user account using EMC" or "Going to the server properties using EMC" or "Opening up the Exchange Management Shell"...
To fix this I had to make sure a few things such as..
- On the problem exchange 2010 server, open up IIS Manager (Start --> Run --> Inetmgr) and verify that under the "Powershell" virtual directory the Module "kerbauth" is installed and the module type set to Native
- Check the same thing for the "Default Web Site" but this time the Module "kerbauth" should not be installed and also click on "Configure Native Modules" on the right hand side and verify that kerbauth is present but un-checked.
- Next verify that the "Environmental Variable" called "ExchangeInstall" is set to "C:\Program Files\Microsoft\Exchange Server\V14\" OR whatever your exchange install path is.
- Finally what actually fixed the issue for me was I went to the IIS logs on my exchange server (C:\Inetpub\wwwroot) and once in that I opened up the "web.config" file using notepad and in that I saw the below line and deleted it but before deleting this make a backup of the file just in case something goes wrong and to be safe!
Once the above line was deleted and the file was saved I no longer encountered the WinRM client error message!!