Windows 11 Update Disrupts Backup Software for Major Vendors
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LONDON (AP) — A critical security update released by Microsoft for Windows 11 has triggered widespread failures in backup software across multiple major vendors, disrupting data protection operations for enterprise and individual users globally.
The issue stems from update KB5083769, distributed on April 30, 2026, as part of the monthly security patch cycle. The update affects Windows 11 versions 24H2 and 25H2, introducing system-wide instability in the Volume Shadow Copy Service (VSS), a core Windows component responsible for creating point-in-time snapshots of files and volumes.
Vendors including Acronis, Macrium, NinjaOne, and UrBackup have confirmed that their backup solutions are unable to complete scheduled tasks on affected systems. The failures manifest as VSS service timeouts, preventing the creation of shadow copies required for reliable data backups. Microsoft has acknowledged the issue is linked to changes in the update’s handling of VSS operations.
The disruption impacts organizations relying on automated backup schedules, potentially leaving systems vulnerable to data loss in the event of hardware failure or cyberattacks. IT administrators report that backup jobs are stalling or terminating prematurely, with error logs citing VSS-related timeouts. Some users have resorted to disabling the update or rolling back to previous versions to restore functionality.
Microsoft has not yet released a patch to resolve the VSS instability. The company’s support pages currently list the issue as under investigation, with no estimated timeline for a fix. In the interim, IT teams are advised to manually verify backup integrity and consider alternative data protection strategies.
The incident highlights the risks associated with widespread software updates, particularly when core system services are modified without sufficient testing across third-party applications. Backup vendors are working with Microsoft to identify the root cause and develop workarounds, but no official resolution has been announced.
Questions remain regarding the scope of the impact beyond the identified vendors and whether other Windows 11 features may be affected. As users await a fix, the outage underscores the critical dependency of enterprise infrastructure on stable operating system updates.