KB4103721 (1803) black screen with rotating circle: potential fix
As many have discovered, installing the KB4103721 rollup to Windows 10 v1803 may result in a black non-responsive login screen with either a rotating circle of white dots or a blue "working" circle. The only way to get your desktop back is to reboot into safe mode, whereupon the update reports it was unable to install and rolls itself back.
If you then use msconfig and disable ALL non-Microsoft services, and reapply the update, you may find that it installs perfectly. This certainly worked for me.
For interest, the non-Microsoft services I disabled were:
- Apple Mobile Device Server (Apple)
- ASUS Com Service (ASUS Motherboard)
- BattleEye Service (ARMA 3)
- Bonjour Service (Apple)
- Dropbox Update Service (Dropbox)
- Google Update Service (Google)
- iPod Service (Apple)
- Logitech Gaming Registry Service (Logitech Mouse/Headset)
- NVIDIA Display Container LS (NVIDIA)
- NVIDIA Telemetry Container (NVIDIA)
- OpenSSH Authentication Agent (Cygwin)
- Steam Client Service (Valve)
- SyncoveryVSSService (Superflexible)
- Syncovery Service (Superflexible)
It is probable that only one of the above caused the problem, but since the update has now successfully installed, I've not had the opportunity to determine which one by enabling them one at a time.
Perhaps someone else can narrow down the culprit and report back.
Hope this helps. ~Speedwaystar