HTTP 400 errors in OWA and ECP and Connection Failure error in PowerShell

Issue:

HTTP 400 errors might occur in Outlook on the Web (OWA) and Exchange Control Panel (ECP) after updates are installed. After you provide credentials to log on to OWA or ECP, the login process may fail with the following error message:

HTTP 400 - bad request Cannot serialize context

Also when you start Exchange Management Shell, you receive the following error message:

ErrorCode : -2144108477TransportMessage : The WS-Management service cannot process the request because the XML is invalid.ErrorRecord

Cause:

This issue occurs if the username ends with the dollar sign ($), such as admin$.

Resolution:

Remove the dollar sign ($) from the username, or use another administrative account that doesn't end with the dollar sign ($).