REDMOND, Washington, January 14, 2026 – Microsoft has issued a second out-of-band update for Windows 11 to resolve Outlook crashes and freezes that began after the January 2026 security update (KB5074109).
The bug primarily affected Outlook Classic users with POP or PST files stored in cloud-backed locations such as OneDrive. Apps attempting to open or save files in these folders became unresponsive or displayed error messages. Some users reported Outlook crashing on launch with error code 0xc0000409, while others experienced hangs, blank interfaces, or search failures.
Microsoft acknowledged the issue shortly after the Patch Tuesday release on January 14, 2026. The company released an emergency cumulative update (no specific KB number disclosed in initial reports) that addresses the problem without requiring additional steps in most cases. Users can download it through Windows Update or the Microsoft Update Catalog.
A temporary workaround involved uninstalling KB5074109 or moving PST files out of cloud storage, though Microsoft advised against long-term reliance on these steps. The update resolves the compatibility conflict without needing a clean boot or registry edits.
This marks the second emergency fix related to the January update. An earlier out-of-band patch addressed shutdown and hibernation failures, as well as remote login issues on some Windows 10 and 11 devices.
Microsoft has not disclosed the number of affected users but described the problem as impacting a subset of systems running Windows 11 version 24H2 or 25H2. The rapid release indicates significant user impact and a commitment to quick resolution.
The company has faced criticism for recurring post-update problems in Windows 11 24H2, including earlier audio, Bluetooth, and performance glitches that required separate hotfixes.
Users experiencing Outlook issues after the January update should check for the new patch in Windows Update settings. If problems persist, Microsoft recommends running the built-in troubleshooter or contacting support.
