In this blog post, you’ll learn more about the Sybase Error Cannot change synchronization user_name when status of the last upload is unknown and the reason for receiving this error
Sybase SQL Error Message
Cannot change synchronization user_name when status of the last upload is unknown
Reason for this Error
The MobiLink server uses the user_name to track synchronizations. If the status of the previous upload is unknown then you must resolve this condition before changing the user.