Microsoft's official support documentation says: "We have investigated a number of issues, and a small number of devices will have a black screen when they are first rebooted after installing the update."Windows10 Version 1809, Windows 10 Enterprise LTSC 2019 and Windows Server 2019 have an impact. The foreign media confirmed that the Windows 10 April update (Version 1803) also had a similar problem after installing the cumulative update KB4503286.
The current temporary solution is that when the device is stuck on the black screen interface, the user only needs to force the device to restart and can properly load and enter the desktop. Microsoft said: "To alleviate this problem, press Ctrl + Alt + Delete, then select the power button in the lower right corner of the screen, then select Restart. Your device should then restart automatically."