Credit: Microsoft

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Summary

• October 2025 updates (KB5066835/KB5066791) can force some PCs into BitLocker recovery.
• Issue hits Intel Modern Standby PCs more; a 48-digit BitLocker recovery key may be required to unlock the drive.
• Microsoft is rolling out a fix; avoid updating until the patch fully deploys to reduce risk.

Drive encryption on Windows is still technically a “business” feature, but if you have Windows 11 Pro, you can fully encrypt your drive using BitLocker. Your TPM is supposed to handle the decryption process on every reboot, which can led to you just forgetting to take care of your keys. Which is a problem if you download the latest Windows update.

Microsoft has confirmed a significant flaw in its recent October 2025 software updates that is causing some Windows 10 and Windows 11 PCs to unexpectedly boot into BitLocker recovery mode. The issue was acknowledged by Microsoft in a support document, which stated, “After installing Windows Updates released on or after October 14, 2025... some devices might encounter issues during restart or startup.” The advisory identifies the problematic patches as KB5066835 for Windows 11 (versions 25H2 and 24H2) and KB5066791 for Windows 10 (version 22H2).

According to Microsoft’s advisory, the problem is not universal. It appears to be disproportionately affecting Intel-based PCs that support a feature called “Connected Standby,” more commonly known as “Modern Standby.” Still, if you’re affected, it’s pretty bad. If you don’t have that key laying around, you won’t be able to unlock your hard drive, and that will lead to the loss of all your data. No other choice than to wipe it clean and start over.

The feature, which will encrypt your whole drive, relies on the user having access to a 48-digit numerical recovery key. This key is required if the system detects a significant hardware, firmware, or software change that could be interpreted as a security threat. The recent Windows update appears to be incorrectly triggering this security check for no apparent reason.

Thankfully, a fix for the bug is already being deployed and it’s coming for affected computers with eligible Windows updates. For most home users, the patch will be delivered automatically via the standard Windows Update service. In the meantime, until this fix is fully deployed, you might want to avoid updating your PC.

Source: Windows Latest