Clarissa Hana
Microsoft has issued a critical alert to users of its Windows operating system, warning that the built-in File History backup feature may cease to function correctly on a significant number of systems following the installation of the September 2026 security updates. This widespread issue affects a range of Windows 10 and Windows 11 versions, potentially leaving users vulnerable to data loss if they rely on this feature for safeguarding their personal files. The company’s acknowledgement of the problem, documented in a service alert, indicates that affected users may encounter application crash events in Event Viewer, specifically referencing FileHistory.exe and KERNELBASE.dll, which point to the root cause of the malfunction.
File History, a feature first introduced in Windows 8 and continued through subsequent iterations of Windows 10 and Windows 11, is designed to automatically create incremental backups of user files. Its primary purpose is to enable users to recover accidentally deleted, corrupted, or lost files by restoring them from a previous version stored from hours, days, or even weeks prior. By default, File History targets critical user profile folders, including Documents, Music, Pictures, Videos, and Desktop, and directs these backups to external storage devices like USB drives or network-attached storage (NAS) solutions. The failure of this core backup utility amidst a series of security patches raises significant concerns about data integrity and system reliability for a substantial segment of the Windows user base.
Unraveling the Technical Glitch: Symptoms and Affected Systems
The impact of the September 2026 security updates on File History manifests in several observable ways. Beyond the application crashes, users may experience misleading "Reconnect your drive" messages, even when their backup drives are properly connected and functioning. A critical indicator of the failure is the "Last Backup" timestamp within the File History interface failing to update, signifying that no new backups are being created. Furthermore, users attempting to restore files may find that older versions are unavailable, displaying the disconcerting message "No previous version available."
Microsoft has identified the specific Windows releases that are susceptible to this File History malfunction. These include:
- Windows 11: Version 26H1, 25H2, 24H2, and 23H2.
- Windows 10: Version 21H2 and 22H2.
- Windows 10 Enterprise LTSC: Versions 2016 and 2019.
The accompanying security updates, identified by their Knowledge Base (KB) numbers, are as follows:
- Windows 11, version 26H1: KB5124012
- Windows 11, version 25H2: KB5124008
- Windows 11, version 24H2: KB5124008
- Windows 11, version 23H2: KB5122880
- Windows 10, version 22H2: KB5122878
- Windows 10, version 21H2: KB5122878
- Windows 10 Enterprise LTSC 2019: KB5122876
- Windows 10 Enterprise LTSC 2016: KB5123099
The breadth of affected versions underscores the pervasive nature of the issue, impacting both consumer and enterprise environments where data protection is paramount.
A Troubled September: A Pattern of Post-Update Instability
The File History issue is not an isolated incident within Microsoft’s September 2026 patch cycle. This month has seen an unusual number of critical problems emerge following the deployment of cumulative security updates. In the week preceding this File History alert, Microsoft was compelled to release out-of-band (OOB) updates to address several other significant disruptions. These included:
- Remote Desktop Services (RDS) Failures: Critical failures impacting the functionality of RDS, a service vital for remote access and management in many organizations, were reported. This issue specifically affected Windows Server operating systems.
- Hyper-V Issues: Problems were observed with Hyper-V, Microsoft’s native hypervisor, affecting host folder shares in Linux virtual machines. This would have hampered development and testing environments reliant on this virtualization technology.
- USB Audio Problems: A number of Windows PCs experienced a complete loss of audio functionality when using USB audio devices, disrupting daily productivity and entertainment for many users.
While Microsoft acted swiftly to release emergency fixes for these aforementioned problems, the company concurrently acknowledged that the OOB updates did not fully resolve all the audio issues. This suggests a complex and deeply rooted problem within the September patch set, requiring ongoing investigation and remediation efforts.
Furthermore, a separate critical bug introduced by the September updates prevented some Windows 11 users from successfully logging into their systems using valid domain credentials. For these users, Microsoft offered a temporary workaround, indicating that a permanent fix was still under development. The recurrence of such significant post-update issues highlights a growing concern regarding the stability and reliability of Microsoft’s monthly security patching process.
Analyzing the Implications: Data Loss and Trust Erosion
The failure of File History, a feature designed to be a safety net against data loss, carries significant implications. For individuals, the loss of personal photos, important documents, or creative projects can be devastating. While many users may employ third-party backup solutions, File History is a readily accessible, built-in tool that a considerable number of users depend on for basic data protection. The fact that this feature is rendered inoperable by a security update intended to enhance system safety creates a paradox that undermines user confidence.
In enterprise environments, the impact can be even more severe. While dedicated backup strategies often exist, the disruption of any automated backup mechanism can create vulnerabilities. If File History was being used as a supplementary or primary backup for specific user data on workstations or even some servers, its failure could lead to compliance issues, operational disruptions, and potential financial losses due to data unavailability or irrecoverability. The subsequent need for manual data recovery or reliance on less frequent full system backups could introduce further risks.
The cumulative effect of these multiple post-update problems also contributes to a broader erosion of trust in Microsoft’s update mechanisms. Users and IT administrators alike are increasingly wary of deploying Windows updates promptly, fearing the introduction of new, unforeseen issues that could outweigh the security benefits. This hesitation can lead to systems remaining vulnerable to security threats, creating a delicate balancing act between immediate security and long-term system stability.
Microsoft’s Response and Path Forward
Microsoft’s acknowledgement of the File History issue through its Windows release health dashboard signifies an official recognition of the problem. The inclusion of specific KB numbers and affected Windows versions allows users and IT professionals to accurately identify if their systems are at risk. The service alert, though brief, indicates that the company is aware of the symptoms and the underlying technical cause.
However, the lack of an immediate fix or a projected timeline for resolution in the initial alert leaves affected users in a precarious position. Given the pattern of recent updates, it is plausible that Microsoft will issue an out-of-band update to address the File History problem, similar to the approach taken for the RDS, Hyper-V, and audio issues. Until then, users experiencing these symptoms are left with a compromised backup solution.
In the interim, IT professionals and concerned users are advised to:
- Verify Backup Status: Manually check the status of File History on all affected systems. Look for the "Last Backup" timestamp and attempt a small file restore to confirm functionality.
- Consider Alternative Backup Solutions: For critical data, users may need to temporarily rely on or implement alternative backup strategies. This could include cloud backup services, third-party backup software, or manual file copying to external media.
- Monitor Microsoft’s Release Health Dashboard: Keep a close watch on Microsoft’s official Windows release health pages for updates and potential resolutions.
- Review Event Viewer: For systems exhibiting issues, examining Event Viewer logs for
FileHistory.exeandKERNELBASE.dllrelated errors can help confirm the problem.
The ongoing challenges with Microsoft’s September 2026 security updates serve as a stark reminder of the complexities involved in maintaining the security and stability of a vast operating system ecosystem. As the company works to resolve these issues, users are left to navigate the immediate consequences, prioritizing data protection through alternative means and awaiting the deployment of reliable fixes. The industry will be observing closely to see how Microsoft addresses this spate of critical post-update failures and what measures will be implemented to prevent similar occurrences in the future. The expectation is for robust testing and validation processes to ensure that security updates enhance, rather than degrade, the overall user experience and system integrity.
