I appreciate that you're trying to find the cause, but the upload program is the same in v6.0.2 and v6.0.4. Version 17 of the upload program was introduced in v6.0.2. The only change that affected MDWS uploads was the addition of HEC's to the uploads. But that only involved the copying of two values from one location to another, and if I'd got that wrong there would be an error message, it wouldn't cause the program to close abruptly.
That's the difficulty in understanding this problem. The small number of coding changes between the two versions wouldn't cause the program to close abruptly, unless I'd done something really gross. If this were the case, it would affect every user, but it doesn't.