Windows 11 April security update is breaking some third-party backup apps

Microsoft’s April 2026 security update for Windows 11 is causing backup failures for some users who rely on third-party backup tools. The issue appears linked to the Volume Shadow Copy Service, better known as VSS, which many backup apps use to create stable system snapshots.

The update in question is KB5083769, released on April 14, 2026, for Windows 11 versions 24H2 and 25H2. It installs OS Builds 26100.8246 and 26200.8246, depending on the Windows version.

The problem does not appear to affect every PC. However, users running tools such as Acronis Cyber Protect Cloud, UrBackup, and Macrium Reflect should check their latest backup logs instead of assuming scheduled backups are completing normally.

What is happening after the update

Several affected users are reporting backup jobs that hang, fail, or time out during snapshot creation. Acronis has acknowledged that Cyber Protect Cloud backups can fail with the message that Microsoft VSS timed out during snapshot creation after installing KB5083769.

UrBackup users have also reported file backups getting stuck after the same Windows update. In some cases, backups appear to stop while the client waits for file list or snapshot activity.

Macrium Reflect users have reported similar VSS timeout behavior in community threads. Some backups retry without VSS writers, but this is not the same as saying the issue is harmless for every setup.

At a glance

Item	Details
Affected update	Windows 11 KB5083769
Release date	April 14, 2026
Windows versions	Windows 11 24H2 and 25H2
OS builds	26100.8246 and 26200.8246
Main symptom	VSS timeout during snapshot creation
Reported tools	Acronis Cyber Protect Cloud, UrBackup, Macrium Reflect

Why VSS matters for backups

VSS is a core Windows component that helps backup tools create a consistent copy of files, apps, and system data while the PC continues running. It coordinates between the backup app, Windows, storage providers, and application writers.

When VSS works properly, backup software can capture a stable snapshot without forcing users to close every app. This matters for system images, database files, open documents, and other files that can change during a backup.

When VSS hangs or times out, a backup may fail completely. In other cases, the backup may continue in a reduced mode, which can make administrators think everything is fine until they inspect the details.

Microsoft has not listed this as a known issue yet

Microsoft’s KB5083769 support page confirms the update details and build numbers. It also lists known issues involving BitLocker recovery prompts in a specific policy scenario and Remote Desktop warning display problems.

At the time of writing, Microsoft’s support page does not list the third-party backup and VSS timeout problem as a known issue. This makes vendor guidance especially important for affected users.

AskWoody raised its MS-DEFCON level to 3 because of the backup reports. That level usually signals caution for patch deployment, especially for administrators managing production systems.

What affected users should check now

• Open your backup software and check the most recent job status.
• Look for errors mentioning VSS, snapshot creation, or writer timeout.
• Run a manual backup test if your last scheduled backup looks suspicious.
• Verify that the backup can be restored, not only created.
• Check your vendor’s support page before removing a Windows security update.

Home users should pay close attention if they rely on image backups before major app changes, driver updates, or Windows upgrades. Business users should also review backup coverage across test groups before rolling KB5083769 out more widely.

IT admins should avoid treating a successful Windows Update installation as proof that backup protection remains intact. The safer approach is to confirm backup completion and restore readiness after the April update.

Should you uninstall KB5083769?

Uninstalling KB5083769 may restore backup functionality for some affected systems, and Acronis lists removal of the update followed by a reboot as a temporary workaround. However, this also removes a security update, so users should not do it casually.

For personal PCs, the better first step is to confirm whether your backup app actually fails after the update. If backups still complete and restore tests pass, removing the update may create more risk than benefit.

For business systems, administrators should follow vendor guidance, document the risk, and use normal patch-management controls. If removal is needed, Microsoft notes that uninstalling combined update packages can require DISM-based removal of the LCU package rather than relying only on older WUSA uninstall behavior.

What this means for Windows 11 recovery

The timing is notable because Microsoft has also been building new recovery features for Windows. Its point-in-time restore feature uses restore points captured through VSS, although that feature remains in preview for Windows client devices.

That does not mean the current backup issue affects point-in-time restore for general users today. Still, the incident shows how important VSS remains for Windows recovery, backup, and restore workflows.

Microsoft also offers Windows Backup, but that tool focuses on files, settings, apps, and account-based restore experiences. It should not be confused with full system image backup tools that depend on VSS snapshots.

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