Overview
- Multiple reports say the KB5083769 security update for Windows 11 versions 24H2 and 25H2 is causing third-party backup jobs to fail.
- Acronis and other vendors link the crashes to a Volume Shadow Copy Service snapshot timeout that stops the backup from ever starting a clean copy.
- Acronis confirms the error message reads “The backup has failed because Microsoft VSS has timed out during the snapshot creation” on Windows 11 Home and Pro.
- Known affected tools include Acronis Cyber Protect Cloud, Macrium Reflect, NinjaOne Backup, and UrBackup Server, while the built-in Windows cloud backup appears to work normally.
- Vendors advise uninstalling KB5083769, rebooting, and pausing updates as a temporary fix, and Microsoft has not yet issued an official explanation or patch after earlier April update troubles on servers and BitLocker.