Application Guard or Windows Sandbox does not open – Error 0x80070003 or 0xC0370400

Some users have been reporting that when they try to open Windows Defender Application Guard or Windows Sandbox on Windows 11/10, it fails to open with error code 0x80070003 or 0xC0370400.

The exact error message is:

• ERROR_VSMB_SAVED_STATE_FILE_NOT_FOUND (0xC0370400)
• E_PATHNOTFOUND (0x80070003).

Application Guard or Windows Sandbox error 0x80070003 or 0xC0370400

If you face this issue where Windows Defender Application Guard or Windows Sandbox on Windows 11/10, here are a few things you could try:

1. Restart your device
2. Install all the pending Windows Updates
3. Run SFC and DISM.

Let us see them in a bit more detail.

1] Restart your device

Restart your device and see if the problem goes away. This simple step has been known to help many.

2] Install all the pending Windows Updates

Check for updates for your computer. Maybe Microsoft has released a fix or an update for your system.

3] Run SFC and DISM

Run System File Checker and DISM and see if they help.

To run SFC, in an elevated CMD execute the following command:

sfc /scannow

In an elevated CMD execute the following command:

Dism /Online /Cleanup-Image /RestoreHealth

This will fix any system image corruption from a Windows Update source.

Incidentally, our freeware FixWin for Windows lets you run both SFC and DISM with the click of a button!

Let us know if anything here helped you.

Related errors:

1. Windows Sandbox Error Code 0x80070002
2. Sandbox Error 0xc030106
3. Sandbox Error 0x80070057
4. Sandbox Error 0x80070015.