Answer:
The error message "System.InvalidCastException: Unable to cast object of type 'System.DirectoryServices.AccountManagement.GroupPrincipal' to type 'System.DirectoryServices.AccountManagement.UserPrincipal'" typically occurs when you try to cast an object of the wrong type.
In this case, it seems that you are trying to cast a GroupPrincipal object to a UserPrincipal object, which is not possible because they are different types. Make sure you are working with the correct type of object and use the appropriate casting method.
Alternatively, you can try using a different approach or method that is better suited to the type of object you are working with.
Step-by-step explanation: