Hi
How was this update pushed to your computer? If it is downloaded manually, please make sure that the Servicing Stack Update KB4566785 is installed before this update.
You could try these methods:
Run elevated Command Prompt
Type in sfc /scannow and wait for it to complete.
Perform Clean Boot, then install the update.
When performing the update, please remove all the external devices connected to your PC.
If you still encounter not boot problem after install update, you could try performing a Starup Repair.
Reference: https://www.partitionwizard.com/partitionmagic/windows-10-not-booting.html
Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
I hope this information above can help you.