Microsoft has issued an emergency update for Windows 11 after a newly reported bug began causing serious stability problems for some users. The issue was described as critical because it could crash Microsoft Outlook under specific conditions, particularly when users stored PST files inside folders synchronized through cloud services. This setup is relatively common in corporate environments, where Outlook data files are often kept in shared or backed-up locations.
The problem appeared shortly after the January 2026 security update was released. Reports indicated that the bug affected applications attempting to open or save files in locations tied to OneDrive integration. Depending on the scenario, affected programs could freeze and stop responding or display unexpected error messages, disrupting normal work routines and productivity.
The new issue is related to Microsoft Outlook (Image: Microsoft).
This is the second time in early 2026 that Microsoft has delivered an “out-of-band” update—meaning a fix released outside the standard monthly patch schedule. Earlier in the year, another emergency package was distributed following complaints from users experiencing failures when shutting down the system, entering hibernation mode, or completing logins through remote connections. Those earlier issues impacted both Windows 10 and Windows 11, raising concerns about system reliability after routine updates.
Out-of-band releases are typically reserved for problems Microsoft considers too severe to postpone until the next scheduled Patch Tuesday update. They are often deployed when a bug affects a large number of users, causes crashes, or interferes with essential services and business operations.
In this case, Microsoft’s emergency update is cumulative, meaning it includes not only the fix for the newly discovered Outlook-related bug but also patches for other recent problems. Users only need to install the latest package to receive all included corrections, including issues introduced by the January security update.
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