Patch Tuesday locked people out of their own PCs, 48 digits at a time
July 2024 updates triggered BitLocker recovery screens at boot for many users
The market's verdict: -2.6% on MSFT in the week after.
What actually happened
The July 9, 2024 cumulative updates sent a wave of machines to a blue BitLocker recovery screen at boot, including dual boot setups, leaving owners locked out unless they could produce a 48 digit recovery key from another device. Microsoft documented the behavior as expected Secure Boot hardening, which is a remarkable use of the word expected, and the fix was entering the key, because no rollback was coming. The same month as the CrowdStrike outage, Microsoft contributed its own lockout and called it a feature of security.
This one is well documented.
Were you affected? Unbreak it
Locked out? Fetch the 48-digit key before anything else
From another device, sign in at account.microsoft.com/devices/recoverykey (aka.ms/myrecoverykey) to find your BitLocker recovery key, enter it at the blue screen, and get back in. Microsoft shipped no rollback for this one; the key is the fix.
Then pause updates until the coast is clear
Settings → Windows Update → Pause updates (up to 5 weeks).
Links
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Impact
- The Verge (publication)
↳ caused by KB5040527 (and July 2024 family)
Timeline
- Jul 9, 2024 Stood by it Microsoft stood by it.