The good news is that while "unhandled exception" sounds like a fatal mystery, it is almost always a sign of a specific, fixable issue like file permissions, disk space, or path settings. This guide will break down exactly what the error means, why it happens, and how to fix it across different emulators and operating systems.
Move both your and your base ROM into this new folder. Run the tool from this location. 3. Check File and Folder Attributes
: Windows Defender or third-party antivirus apps block the program from modifying disk files.
An means the program encountered a problem for which it had no defined handler. When trying to save a ROM, the program performs many low-level operations: opening a file stream, requesting write permissions from the OS, writing raw bytes to specific sectors on a storage device, and then closing the stream. The good news is that while "unhandled exception"
ERR-ROM-2026-04-18-01 Date of Occurrence: April 18, 2026 Reported By: System / User Affected Component: Emulator / ROM Management Module Severity: Medium – User data loss possible; operation interrupted
"There was an unhandled exception trying to save your ROM to disk. A log file containing some details has been saved to error_[date]-[time].txt." Common Causes and Solutions Based on user reports on , this error occurs for several specific reasons: Overwriting an Existing File
The error arises during a specific phase: after you've selected your desired randomization settings and click the "Randomize (Save)" button. The software runs a series of operations to modify the ROM's data, which it then attempts to write as a new file to your disk. If any part of this process fails—whether in the data processing or the file-writing stage—the "unhandled exception" message appears. Run the tool from this location
| Area | Impact | |------|--------| | User Data | ROM changes or progress lost if not saved elsewhere. | | Workflow | User cannot complete save operation; retry attempts may fail. | | System Stability | No crash beyond the exception; application may remain responsive or partially hang. | | Frequency | Intermittent – depends on environment conditions (permissions, disk space, etc.). |
) in the same folder as the program. Opening this can provide a specific technical traceback for developers if you need to report a bug on GitHub [Bug] Issue by 'Randomize (Save)' #771 - GitHub
Here’s a structured incident report regarding the error: “There was an unhandled exception trying to save your ROM to disk.” An means the program encountered a problem for
: If possible, use an English (USA) version of the ROM, as these typically have the highest compatibility across all randomizer versions. Run as Administrator
Rare but possible: bad sectors on a hard drive, or a file system that needs checking ( chkdsk on Windows, fsck on Linux/macOS).