When trying to open the Control Panel for the entire sites on a Windows Server, the action fails.
One of the reasons is that php is not working for the primary VDS.
Verify this by implementing a new php file under the primary VDS and try to browse to it from the IIS ().
If the file cant be seen, it might indicate some kind of php failure.
The source of the problem might be with the php extension: the parameters might not be identical for the P.VDS and under Web Service Extension for php.
Verify the string is identical in both locations, even a small character like inverted commas must be consistent see the attached picture.