Hi Sam,
There are a lot of reasons as to why this would happen. A conflict with hardware, (doesn't support the latest version of Windows), outdated drivers, or even software conflict (third party antivirus programs, manufacturer's pre-installed programs, etc.) are just a few of them.
Since bugs are inevitable, what you can do is to create a back up. This will assure that you will always have something to go back to in case things went south. Here's an articlefor your reference.
You may also run the Windows Update troubleshooter to fix system file corruption that causes you to experience issues after installing an update.
Best regards.
I didn't get a chance to back up my files when the update was installed without my knowledge or ok