Is it possible that you've created some new classes? Or are trying to use the wrong version of the cmdlets against the service?
it's hard to tell from this message, but you should be able to get more detail via $error. Immediately following this error, try looking at the contents of $error
$error[0]|fl -force
$error[0].Exception|fl -force
$error[0].Exception.InnerException|fl -force
it's hard to tell from this message, but you should be able to get more detail via $error. Immediately following this error, try looking at the contents of $error
$error[0]|fl -force
$error[0].Exception|fl -force
$error[0].Exception.InnerException|fl -force