Microsoft has released an emergency update, KB5078127, to resolve critical issues causing Outlook to crash or fail to launch. The update follows the problematic January patch KB5074109, which affected users across Windows 10, 11, and Server editions as far back as 2019.
Update and Impact
The new update specifically targets Outlook users experiencing problems due to PST files stored in cloud-accessible folders like OneDrive. Some users reported that the applications became unresponsive or did not open. The emergency update effectively addresses these launch and crash issues, providing relief for many users who rely on Outlook for daily tasks.
While KB5078127 solves several urgent problems, some known bugs, such as those affecting File Explorer, persist. These remaining issues are anticipated to be fixed in the next scheduled update on 2026-02-10.
Steps for Users
Users experiencing issues with Outlook are advised to install the KB5078127 update by navigating to Settings > Windows Update. This corrective measure ensures the stability and functionality of affected applications.
- Microsoft released KB5078127 on 2026-01-26 to fix Outlook.
- The update addresses crashes caused by KB5074109 in cloud-stored PST files.
- Affected users are on Windows 10, 11, and Server editions since 2019.
- Remaining File Explorer issues will be addressed by 2026-02-10.
- Users should update via Settings > Windows Update.
