Immediate steps to try
Windows Defender’s Controlled Folder Access (introduced in Windows 10) can block emulators from writing to your Documents, Pictures, or Downloads folders. What would improve it
The emulator does not have permission to write files into the folder where it is installed. Follow these solutions in order, as they move
If I were to grade it as a user experience, it gets points for honesty and theatrical timing, but fails spectacularly at empathy and utility. What would improve it? A hint, a link to a log, or even a tiny “Try these steps” checklist. Better yet, an acknowledgement of the human on the other side: “We know losing work is awful — here’s how to attempt recovery.” Follow these solutions in order
In simple terms, when you see "There was an unhandled exception trying to save your ROM to disk," the tool you're using—whether it’s a randomizer, an emulator, or a ROM editor—has encountered an error it was not programmed to handle while trying to write data to a file on your hard drive, SD card, or USB storage device.
Follow these solutions in order, as they move from the most common to the most complex. Solution 1: Run Emulator as Administrator
The save file or the folder it is in is set to "Read-Only," preventing updates.