Outlook users have reported difficulties with Microsoft’s January Patch Tuesday updates, forcing Microsoft, once again, to patch some of its patches.

Users reported that, after applying the January 13 Windows updates, some applications became unresponsive or encountered unexpected errors when opening files from or saving files to cloud-based storage such as OneDrive or Dropbox. In particular, certain Microsoft Outlook configurations with the PST file containing a users’ messages stored on OneDrive could cause Outlook to hang or lead to sent messages going missing or previously downloaded emails being re‑downloaded.

In response, Microsoft has issued a bunch of out-of-band emergency updates for Windows 11 and 10 and Windows Server 2019, 2022, and 2025 to solve the problem.

This is not the first time that Microsoft has had to issue a patch for a patch. Just last week, it had to react when it inadvertently introduced two new bugs: an inability to connect to Windows Cloud PCs and an inability to shut down some machines with Secure Launch enabled. Prior to that, in October 2025, a patch caused a multitude of different issues, while in May 2025 Microsoft had to issue an out-of-band patch to fix a Windows 11 start-up failure.

Microsoft said the latest out-of-band updates are cumulative and include security fixes and improvements from the January 13, 2026, security update (KB5074109) and the out-of-band update (KB5077744) from January 17, 2026.