“Connecting to remote server failed with the following error message: The WinRM client cannot process the request. It cannot determine the content type of the HTTP response from the destination computer. The content type is absent or invalid. For more information, see the about_Remote_Troubleshooting Help topic.”
Have recently been on an engagement where we have had to perform an in place upgrade from Windows 2008 R2 Standard edition to Windows 2008 R2 Enterprise edition whilst Exchange 2010 was installed to facilitate the addition of a DAG.
All went well but the above error was received when we launched the Exchange MC. After a bit of head scratching I realised that the WinRM IIS component wasn’t selected anymore???? Added the feature and all started working again, magic.