Microsoft Issues KB5078127 OOB Patch After Reports of Outlook Freezing and File System Instability
Microsoft has issued two critical out-of-band (OOB) security updates to address significant issues affecting Windows 11 users following the January security updates.
Microsoft has issued two critical out-of-band (OOB) security updates to address significant issues affecting Windows 11 users following the January security updates.
The emergency patches, identified as KB5078127 and KB5078132, resolve severe file system failures and application crashes that were reported after the January 13 security release.
The root cause of these issues was traced to complications introduced by patches KB5073455 and KB5074109, which led to problems with cloud-based file storage operations.
Applications accessing or saving files to cloud storage services such as OneDrive and Dropbox experienced critical errors, becoming unresponsive. Outlook users storing PST files on OneDrive faced issues with the email client hanging indefinitely, necessitating forced termination or system restart. Users reported missing sent items and reappearing previously downloaded emails, indicating potential PST file corruption or synchronization failures.
Microsoft addressed the file system regression introduced during the January security updates by deploying emergency fixes approximately 11 days after the initial release. This action underscores the severity of the impact on Windows 11 users.
Patch KB5078127 targets Windows 11 versions 25H2 and 24H2 (OS Builds 26200.7628 and 26100.7628), while KB5078132 addresses version 23H2 (OS Build 22631.6495). Both patches are available through Windows Update and the Microsoft Update Catalog.
Applications accessing or saving files to cloud storage services such as OneDrive and Dropbox experienced critical errors, becoming unresponsive.
Users with automatic updates enabled will receive these patches automatically. Others must manually navigate to Settings > Windows Update to install the updates.
Patch Number Affected Windows 11 Versions OS Build Numbers Primary Issue Fixed Includes
KB5078127 v25H2, v24H2 26200.7628, 26100.7628 File system instability, Outlook PST freezing on OneDrive KB5074109, KB5077744
KB5078132 v23H2 22631.6495 Cloud storage file access errors, Outlook hang issues KB5073455, KB5077797
A minor known issue exists in KB5078127 where the password icon may be missing from lock screen sign-in options. This is a cosmetic issue and does not affect authentication functionality.
Enterprise administrators managing Windows 11 devices via Microsoft Intune or Windows Autopatch should expedite deployments by following platform-specific update acceleration guidelines. IT departments should prioritize this patch for users reporting Outlook freezes or cloud storage access failures.
Both patches include cumulative updates with servicing stack updates (SSU); as a result, they cannot be partially removed after installation. Users cannot uninstall the SSU component separately.
Based on reporting by GBHackers.