Why do I get Error when syncing Project with Project Transit?

Symptoms

When syncing an MSP project with Daptiv Project Transit, user is getting error from the wizard such as

"System.Runtime.InteropServices.COMException (0x800A044D): The argument value is not valid."

This is not linked to the Microsoft project version.

Resolution

1. Open the file in MS Project then go to File > Info > Project Information > Advanced Properties > Custom Tab > Properties Box (Scroll Down and select PTProjectID)
2. Delete the Value in the Value field > OK
3.Re-save.
4. Then try to re-sync.