Some users of newer versions of Windows 10 are currently faced with the problem that both the built-in sandbox and the Windows Defender Application Guard (WDAG) crash with two different error codes. Microsoft has confirmed the problem and wants to publish an update. When it will be available is still open.
Security features especially for companies
The Windows Sandbox offers a virtualized Windows 10 environment for testing applications; it was only introduced a year ago in Windows 10 version 1903 (Pro, Enterprise and Education). WDAG is a security extension available for various browsers. It causes websites defined as untrustworthy to be opened via Microsoft Edge in an isolated, Hyper-V-capable container. WDAG is supported from Windows 10 version 1803 (also Pro, Enterprise and Education).
Since neither Sandbox nor WDAG support Windows 10 Home Edition, the current crash problems primarily affect users in corporate environments and in the vicinity of educational institutions.
Both features occasionally caused crash problems in the past. Among other things, the sandbox was unusable for months due to a bug after its release by German users.
Problems confirmed, fix planned
When starting the Windows Sandbox or when using the Windows Defender Application Guard, it can currently happen that the functions with the error code 0x80070003 or the error code 0xC0370400 crash and stop working. The error code 0x80070003 stands for E_PATHNOTFOUND and indicates incorrect path information in an internal call. The second code (0xC0370400) stands for ERROR_VSMB_SAVED_STATE_FILE_NOT_FOUND.
In one Support document for the error messages Microsoft confirmed the problem on July 24, 2020. As a workaround, the company recommends simply restarting Windows 10. However, according to experience reports on the Internet, this procedure does not always seem to help. Microsoft says it is currently working on a problem solution. The fix is to be delivered via Windows 10 update when it is finished.