Windows Sandbox has stopped working recently, despite no changes to the system or software. When launched from the Start Menu, it shows the Windows Sandbox splash screen (blue sandbox icon on a gray background) for several minutes, then it shows Windows Sandbox window (as in, a window frame with the title bar at the top) but it's totally black and unresponsive inside. After a few more minutes, it crashes and one of two error message boxes appear:
Windows Sandbox failed to connect.Error 0x80072746. The connection to the sandbox was lost.An existing connection was forcibly closed by the remote host.
Windows Sandbox failed to connect.Error 0x800705b4. This operationreturned because the timeout period expired.
It is worth noting that the line "The connection to the sandbox was lost" is what would normally appear in a similar messagebox when I would manually close a Windows Sandbox instance (back when it was working properly on my device).
After closing the error message box, "WindowsSandbox.exe" remains running in Task Manager. It must be manually terminated before trying to launch Sandbox again.
Windows Sandbox was working fine until a few days ago, and as mentioned, nothing has changed recently about my computer. Windows Update has not had any new updates since well before this problem arose. I have run sfc /scannow and dism /online /cleanup-image /restorehealth but both found no issues. I have launched "Turn Windows features on or off" (OptionalFeatures.exe) and have tried disabling Hyper-V and Windows Sandbox, rebooting, re-enabling them, and rebooting again, with no effect. I have confirmed that virtualization is enabled in BIOS.
The OS is Windows 11 Enterprise 64-bit, build 22631. Launching Properties for WindowsSandbox.exe and going to Details shows the version is 10.0.22621.2506.