Microsoft fixed login and startup errors in the new Windows 11 update

Microsoft released a cumulative preview update KB 5074105 for Windows 11

> Preview patches that are released before the official Patch Tuesday are not intended for security, but rather to improve OS quality.

> They give administrators the opportunity to test new fixes and features several weeks before they are widely deployed.

What the KB 5074105 update includes
Category Action Issue Fixes
• Explorer hangs on first logon
• OS boot failure if Windows Boot Manager debug mode is enabled
• iSCSI error with “Boot device unavailable” message

Activation and licensing
• Fixed an issue that caused license migration to fail (PC could not register with the activation server)

Build updates
After installation, the update raises build numbers to:
• Windows 11 25H2 → 26200.7705
• Windows 11 24H2 → 26100.7705

How to install
1. Open Windows Update and check for updates.

2. In the list select “Download and install” (the update is not mandatory).

3. Alternatively, you can download the package manually from Microsoft’s update catalog.

Why this matters for administrators
- Preview patches give time to test changes in a safe environment.
- Unlike Patch Tuesday, they do not contain security fixes and are solely aimed at quality improvement.
- New KB identifiers for Windows 11 and Windows Server 2025 (starting with January 2026 updates) help avoid confusion: each product has its own set of build numbers.

Conclusion
Microsoft continues to refine Windows 11 by giving administrators the chance to pre‑test critical fixes. The KB 5074105 update is a step toward more stable and secure OS performance in the month leading up to the official Patch Tuesday release.