If Windows update keeps failing, identify which update or updates keeps failing.
It should say or look something like this: KB4041676
Visit the Microsoft®Update Catalog by selecting this link and search for the Update(s):
It will give you multiple results but select the one that’s relevant to your operating system and matches the closest to the update that windows says is failing.
Once selected the file will be downloaded and you will want to run the install.
If that did not work then reach out to experts, HelpCloud Technician by-the-hour.