Many people have reported issues with Windows Update, whether the update gets stuck or fails. First, you’ve upgraded to the Windows 10 Fall update (see Can’t upgrade to the latest Windows 10 version). If you still have problems, download and run the Windows Update Troubleshooter, reboot, and try to update again.
If the problems continue, you might need to consult Microsoft Support or feel free to contact OpenTech Support. First, check that System Restore is configured and create a restore point. Then, use Win + X and select Command Prompt (Admin), then type ‘net stop wuauserv’ (without the quotes) and hit Enter, followed by ‘net stop bits’ and Enter. You should see confirmations that each service has stopped or wasn’t running. Next, open Explorer and navigate to C:\Windows\SoftwareDistribution. Delete its contents, including any sub-folders. Now reboot, open Windows Update, and click Check for updates.