what happens when you deactivate a user who owns some appian objects?

Some of the expressions / functions might stop working with a privilege exception, if a User who owns the objects is de-activated.

As a general rule, it is recommended that you use Groups to define security for Appian Objects:
forum.appian.com/.../Appian_Object_Concepts.html

Thank you Alok.

@ajays Added to Alok's explanation 'Some of the expressions / functions might stop working with a privilege exception', there are some more and they are infact much crucial as follows:
>> https://forum.appian.com/suite/help/7.9/User_Management.html#Deactivating_Users

>> Tasks assigned to a user remain assigned to that user even after the user is deactivated. If the user is reactivated, the user will continue to see the task. ('Best Practice' at https://forum.appian.com/suite/help/7.9/Assignment_Tab.html')

Hope it adds some more information to your question.

You also get errors if any user you are adding using Add Group Members smart service and that user has been de-activated.

Thank you for the information.

Hi Ajay,
In our case we are managing deactivation of user through process model, So that you can perform all the prerequisite changes(e.g reassigning task to some one else) before deactivating user .
And Best practice is to manage all user management action through processes
Thanks
Ajinkya