Microsoft’s KB5127936 preview (dated 28 October 2026, builds 26300.9818 / 26200.9818 for Windows 11 26H2 / 25H2) lists a Windows Sandbox fix: Sandbox might close unexpectedly and display error 0x80370106 while in use.
This topic is about that in-use crash/close, not about being unable to enable Windows Sandbox (a different intent already covered elsewhere on the site).
Confirmed points
- [Windows Sandbox] item under normal rollout on KB5127936: addresses unexpected close with 0x80370106 while in use
- Non-security preview package dated 28 October 2026 for Windows 11 25H2 and 26H2
- Documented install path: Settings > Windows Update > Advanced options > Optional updates (per the KB)
- Starting with the October 2026 release, non-security preview updates are no longer aimed at Windows 11 24H2 the same way (Enterprise / Education continue monthly security updates)
No hands-on Sandbox lab test is claimed here. On a managed PC, ask IT before installing an optional update.
Sources
Question: have you seen Windows Sandbox close with 0x80370106 while in use, and did KB5127936 stabilize Sandbox once deployed?