Microsoft working on a fix for Windows 10 Sandbox failing to open

Microsoft is investigating a known issue preventing the Windows Sandbox and Windows Defender Application Guard (WDAG) from opening on some Windows 10 devices.

Windows Sandbox allows Windows 10 users to run applications within a completely isolated desktop environment, separately from the host machine.

WDAG protects Windows 10 and Microsoft Edge users against emerging online attacks while they are browsing the Internet by opening untrusted sites within isolated Hyper-V-enabled containers.

According to a support document published by the company earlier today, the two apps will throw the following errors after failing to start on affected systems:

According to Redmond's support document, devices running Pro and Enterprise editions of Windows 10, version 1903, 1909, and 2004 are currently affected by this issue.

Users who can't open WDAG or the Windows 10 Sandbox can mitigate the issue after seeing one of the above error messages by restarting their device.

After rebooting, the two apps should launch without any problems according to Microsoft's support document.

Microsoft says that it's currently working on a resolution to address this known issue, with a fix to be provided as part of a future release.

An almost identical problem affected the Windows Sandbox last year when Microsoft said that the app failed to open on devices where customers installed the KB4497936 Cumulative Update for the Slow, Fast, and Release Preview rings of the Window Insider program.

As described by Microsoft at the time on the Windows 10 health dashboard, "Windows Sandbox may fail to start with 'ERROR_FILE_NOT_FOUND (0x80070002)' on devices in which the operating system language is changed during the update process when installing Windows 10, version 1903."

Earlier this month, the company fixed another known issue causing Local Security Authority Subsystem Service (LSASS) crashes and forced system restarts on some Windows desktop and server devices with the release of the KB4565503 cumulative update released as part of July 2020 Patch Tuesday.

Microsoft also removed a Windows 10 2004 update block after resolving an issue that was triggering stop errors and blue screens when plugging or unplugging Thunderbolt docks