Microsoft has been forced to issue another urgent, unscheduled update for Windows 11 to fix major problems caused by its own recent security patches. This is the second "out-of-band" emergency update the company has released in January 2026, highlighting a particularly messy update cycle.

The latest fix, identified as KB5078127, addresses a serious bug that was making several popular applications freeze or crash. The problem primarily affected programs that rely on cloud storage, including Microsoft Outlook, OneDrive, and Dropbox.

For some users, Outlook would hang on launch, refuse to reopen, or start re-downloading old emails. The issue was triggered by the January 2026 security updates, specifically when users had their Outlook data files (.PST files) stored in folders that sync with cloud services—a common setup in many workplaces.

Microsoft's initial, temporary workaround for affected users was to uninstall the January security updates, which is far from ideal as it leaves systems unprotected. The new emergency update, KB5078127, is intended to be a permanent fix and bundles in the patches from both the original January update and the first emergency fix released earlier in the month.

The first emergency update, KB5077797, was released on January 17 to fix a different problem: a bug that prevented some PCs from shutting down, restarting, or going into hibernation mode after the January patches. It also addressed Remote Desktop login failures. Unfortunately, that first fix reportedly introduced the new bug affecting Outlook and cloud apps.

Microsoft reserves these out-of-band updates for critical issues that are too disruptive to wait for the next scheduled "Patch Tuesday" update. The back-to-back emergency releases have raised concerns about the stability of Windows 11 updates and put pressure on Microsoft to ensure the February 2026 security updates are more reliable.