The Windows 10 KB4507453 Cumulative Update released by Microsoft on July 9 is reportedly causing a restart notification loop on some of the computers where it was installed.

This issue was reported by Windows users on several websites and computer support forums across the web [1, 2, 3], with all of them describing the exact same problem — being told to reboot their devices again to finish installing the KB4507453 update even though it was already installed.

While multiple Windows 10 Version 1903 and Windows Server Version 1903 users have been already impacted by this issue according to their reports, Microsoft has not yet publicly confirmed the restart notification loop problem they experienced.

Not all systems where KB4507453 is installed to be affected

Also, according to German blogger Günter Born who initially reported the reboot loop issue, not all users of Windows 10 version 1903 who install this cumulative update will be affected given that he wasn't able to reproduce the bug on his test systems.

The update information doesn't include any info on changes made to the Windows 10 notification system or the update installation procedure that could be behind this glitch.

As detailed on the KB4507453 update's entry on Microsoft's support website, it comes with the following highlights:

Addresses an issue that may cause BitLocker to go into recovery mode if BitLocker is being provisioned at the same time as updates are being installed.

Addresses an issue that may cause Mixed Reality users to see a tilted world after connecting their headsets.

Addresses visual quality issues some users may have seen with Windows Mixed Reality (WMR) headsets and Steam®VR content.

Security updates to Windows Wireless Networking, Microsoft Scripting Engine, Windows Server, Windows Storage and Filesystems, Windows Kernel, Microsoft HoloLens, Internet Explorer, Windows Input and Composition, Windows Virtualization, Windows App Platform and Frameworks, Microsoft Graphics Component, Microsoft Edge, and Windows Cryptography.

Available workarounds

Born says that there are at least two possible workarounds to get rid of the irritating alerts continuously nagging users to restart their systems.

The first is to click the "Restart Now" button on the notification dialog itself generated by the Windows 10 Notification Center instead of trying to restart the system from the Start menu.

A second workaround consists of checking again for system updates via Windows Update, as discovered by heise online's Jan Schüßler. This allows the OS to see that no new updates are available and that no other restarts are needed given that all previous updates were installed.

This might also happen on its own after some time once Windows will check for updates on its own, although it may take hours for some of the affected Windows users.

More issues caused by July's Cumulative Updates

Other monthly rollups, security-only updates, and cumulative updates (i.e., KB4503293, KB4503327, and KB4503286) released on June 11 are behind an issue already confirmed by Redmond and impacting multiple Windows 10 Server versions.

This new known issue acknowledged today by Microsoft may block devices from booting if they're using Preboot Execution Environment (PXE) images from Windows Deployment Services (WDS) servers or System Center Configuration Manager (SCCM).

Cumulative update KB4507469 is behind another known issue causing a small number of devices to potentially "startup to a black screen during the first logon after installing updates."

To bypass this black screen, users can "press Ctrl+Alt+Delete, then select the Power button in the lower right corner of the screen and select Restart," with the device restarting normally afterwards.

Microsoft says that is currently working on resolutions for both these known issues, to be made available with an upcoming Windows 10 release.