From where are you running the form? From Object Designer? From another form?
The error is the result of an uncaught error with the GET command. When you don’t check to see if it was actually able to retrieve a record it throws an error like “The does not exist. Identification fields and value: …”
You need to be out of Nav when deleting the ZUP file otherwise it resaves on exit. Turn on the debugger if deleting the ZUP file doesn’t work and find out where the error is occuring.