Windows 11’s built‑in Sandbox feature has been hit by a widespread bug that makes it completely unusable for many users. Reports show the tool stalls at launch for nearly ten minutes before failing with error 0x800705b4, even after reinstalling the feature or running SFC/DISM scans. Multiple Windows 11 builds appear affected, and users across Microsoft Q&A, GitHub, and forums say they’ve been waiting weeks for an official fix.
On Windows 11, the Windows Sandbox features have been broken for some time. However, this issue is flying under the radar because Microsoft has yet to acknowledge it or provide answers to affected users.
This alleged bug wasn’t reported only on GitHub, but across the web. You can find reports on Reddit. On another Reddit thread, @Kranorzor noted, “Stuck at loading splash screen for 5-10 minutes then gives this error.”
I also found reports of the same error on the Microsoft Q&A forum, where Michael Higham said, “When I start Windows Sandbox, it stalls at the logo for ten minutes or so, and then an error message shows up.”
You can even find complaints and reports in other forums.
How to fix Sandbox with error 0x800705B4 on Windows 11
Although it’s not a conventional solution, on GitHub, the same person who reported the bug explained that a solution involves reinstalling the operating system through recovery settings using these steps:
- Open Settings.
- Click on System.
- Click the Recovery page on the right side.
- Click the Reinstall now button for the “Fix problems using Windows Update” setting.
- Check the “Automatically restart my PC 15 minutes after installation” option.
- Click the OK button.
Once you complete the steps, the operating system will be reinstalled with the same version already installed on the computer, preserving your files, apps, and settings.
This isn’t the only concern. The quality of recent updates has been questionable lately. For example, the January 2026 Security Update (KB5074109) has caused app crashes, triggered black screens on devices with NVIDIA GPUs, and even broken the Outlook app on Windows 11.
Microsoft also released an Out-of-band (OOB) update, KB5077744, for versions 25H2 and 24H2 to fix sign-in failures during Remote Desktop connections.
Until Microsoft issues a patch (or tries this fix), Windows Sandbox is effectively dead for anyone encountering the timeout bug — and with reports spanning multiple builds and configurations, it’s clear this isn’t an isolated glitch. For now, users can only wait and hope the next update finally restores one of Windows 11’s most useful security and testing tools.
If you’ve hit the 0x800705b4 Sandbox bug — or found a workaround that actually helps — drop it in the comments. Curious how widespread this is and whether anyone’s managed to keep Sandbox usable on recent builds.
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