users explain that KB4103721 installs correctly and after the first boot, it pushes the device to a black screen. According to one Reddit user: The issue was first reported on Microsoft Community forum and since then several users have shared all sorts of different errors with the latest update. However, Microsoft hasn’t officially acknowledged the issue or shared anything regarding this matter. If you’re facing this issue then you can go to safe mode and restore back to the point before installing the update. Then disabled that update (KB4103721) for now using the ‘Download the “Show or hide updates” troubleshooter package now.‘ package from MS. Or completely uninstall windows 10 version 1803 and downgrade (In Advanced options, click “Go back to the previous build” ) to Windows 10 Fall Creators Update version 1709. However, restoring will work only if you haven’t deleted the windows.old and $windows.~bt folders from the system. https://windows101tricks.com/delete-windows-old-folder-freeup-disk-space-windows-10/ This should serve as the temporary fix until Microsoft acknowledges the issue and releases a permanent fix. For now, it would be suggested to stay away from the latest cumulative update. Also Checkout this Startup Stuck At Black Screen With Cursor After Upgrade
