April KB5083769 Windows 11 Update Causes Backup Software Failures

The April 2026 KB5083769 security update for Windows 11 is causing widespread failures in third-party backup applications, according to user reports and vendor advisories. The issue affects systems running Windows 11 24H2 and 25H2, with backup software that relies on the Volume Shadow Copy Service (VSS) experiencing timeouts and failures.

Microsoft VSS, introduced in Windows Server 2003, coordinates backup operations between the OS, backup software, and business applications like SQL Server and Exchange. The KB5083769 update appears to introduce a VSS service timeout, causing backup operations to fail with errors such as "The backup has failed because Microsoft VSS has timed out during the snapshot creation."

Affected products include Acronis Cyber Protect Cloud, Macrium Reflect, NinjaOne Backup, and UrBackup Server. Acronis has published a support document confirming the issue, noting that in some cases, the affected machine may also lose connectivity with the cloud console and appear offline.

As a temporary workaround, users are advised to uninstall the KB5083769 update via Settings > Windows Update > Update history > Related settings > Uninstall updates, then pause Windows updates and reboot the system. Microsoft has not yet responded to requests for comment.

This incident follows other recent Windows update issues, including out-of-band updates to fix restart loops on Windows Server and BitLocker recovery prompts on Windows Server 2025 after installing KB5082063. The recurring pattern of update-related disruptions highlights the challenges of maintaining system stability while delivering security patches.

For organizations relying on backup software, this update poses a significant risk to data protection and recovery capabilities. Until Microsoft provides a permanent fix, administrators must weigh the security benefits of the update against the operational impact on backup systems.