When attempting to upgrade or remove the CA DataMinder Exchange Server Agent the process may fail with the following error:
Error 25170. Error unregistering with Exchange Server: Unknown error 0xffff0000 (-65536) (code 0xffff0000). Ensure that you respond to any PowerShell windows and the current execution policy is not Restricted.
This issue arises when the Microsoft Exchange Management PowerShell has not been installed on the Exchange Server.