When you receive Windows Update error 80073f8f while checking for updates, your computer’s date and time might not be the same as the date and time for the online Windows Update service. Your computer and the service don’t need to have an identical date and time but if they vary too much it will prevent you from checking for updates.

To resolve this issue you need to change machines’ date and time. If your time zone observes daylight saving time and you want your machines’ clock to be adjusted automatically when daylight saving time changes, on the Date and time tab, click Change Time Zone and then make sure that the Automatically  adjust clock for Daylight Saving Time checkbox is selected.