All pages on Administrative portals work except the Roles.
An error occurred on the server when processing the URL. Please contact the system administrator.
If you are the system administrator please click here to find out more about this error.
This happens because of invalid IIS settings.
Please go to IIS manager
Locate the web-site that is hosting the PM virtual directory
Navigate to admin virtual directory
Open ASP settings under IIS section.
Make sure that Enable Buffering is set to True.