"An operating system wasn't found", said the operating system's update
March 2025 update broke booting on some Lenovo laptops
The market's verdict: +1.2% on MSFT in the week after.
What actually happened
The March 2025 cumulative update for Windows 11 24H2 could leave certain consumer Lenovo laptops staring at "An operating system wasn't found" on boot, because the update disabled a firmware setting the laptop needed to find its own disk. The recovery procedure involved digging through BIOS screens to re-enable what a Patch Tuesday had switched off. Lenovo documented the workaround; Microsoft supplied the surprise. Between this and the BitLocker month, 2024 and 2025 spent serious energy teaching users what a BIOS is.
This one is officially acknowledged.
Were you affected? Unbreak it
Lenovo's fix: re-enable the boot option in BIOS
Enter BIOS/UEFI setup at boot and re-enable the setting the update switched off (Lenovo's support page lists the exact option per model), let the machine boot, then uninstall KB5053598 so the next Patch Tuesday does not do it again.
Uninstall the March update once booted ↗
wusa /uninstall /kb:5053598 /quiet /norestart
Links
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Impact
- BleepingComputer (publication)
↳ caused by KB5053598
Timeline
- Mar 13, 2025 Mitigated Microsoft put safeguards around it.