Here is an easy fix to a failed KB4054517 update
- Go to Settings > Update & Security > Windows Update > click Viewed installed update history
- Click Uninstall updates
- Click Security Update for Microsoft Windows (KB4054517)
- Click Uninstall (this might take a while)
- Reboot (it'll say it's updating)
- After it reboots go to Go to Settings > Update & Security > Windows Update > Check for updates
- KB4054517 is shown as an update
- Update > it reboots and installs the update
- After rebooting go to Settings > Update & Security > Windows Update > click Viewed installed update history
- KB4054517 successfully installed
- OS Build 16299.125
- This might work for any failed update, couldn't say for sure as this was my first failed update