When this happens to OWA, do this in Exchange PowerShell:
Remove-OwaVirtualDirectory "EXCHANGESERVERNAME\owa (default web site)" New-OwaVirtualDirectory
This came from here:
When this happens to OWA, do this in Exchange PowerShell:
Remove-OwaVirtualDirectory "EXCHANGESERVERNAME\owa (default web site)" New-OwaVirtualDirectory
This came from here: