A number of users have recently reported FATXplorer v3.0 beta suddenly failing to start. No error message is shown and FATXplorer is not able to be used. Affected users will find this in their Windows Event Viewer Application error logs: The process was terminated due to an internal error in the .NET Runtime at IP xxx (xxx) with exit code 0x80131506.

FATXplorer v2.5 is unaffected by this.

The Cause

The .NET 8.0.3 runtime has a bug where a specific CPU instruction, when run on unsupported/older CPUs (like the Intel Core 2 series), will cause a crash. .NET 8.0.3 can be delivered via Windows Update in the background, explaining why FATXplorer is suddenly crashing when it previous worked before.

The Fix

The full fix will be delivered via .NET 8.0.4, which is scheduled for release on April 9th, 2024 at 1 PM EST. In the meantime, a temporary workaround is available:

  1. Go into your apps/installed programs and uninstall: Microsoft Windows Desktop Runtime – 8.0.3
  2. Install the older 8.0.2 runtime version:
  3. FATXplorer should now work. You may want to temporarily suspend Windows Updates until April 9th, 2024 so the 8.0.3 runtime doesn’t get automatically installed again.

If you are having this problem after April 9th, 2024, check for Windows Updates and it should take care of the problem.