"file can not be saved, because it doesn't exist"

There was a thread last fall about this topic. This is not a Panorama problem, it is a system problem, most likely whatever folder the file is in does not have the correct permissions. That error message is not a Panorama error message, the message comes from Apple’s code. (Panorama X relies on Apple’s code to a much larger extent that Panorama 6 did – for example all reading and writing of databases is handled by Apple’s code.)