Doing a few Bing/Google searches on the error number make sure the date and time is correct on the phone and if that doesn't work you'll have to do a hard reset; wiping the phone to factory defaults. Make sure you backup everything you want to keep.
It seems to be a known issue that HTC nor Microsoft has answer for.
Make sure there is enough room on your phone for the update. You may need to uninstall some of the games (especially the large ones) to make room for the installer. You can always reinstall them after the update. If you photos are uploaded to OneDrive, perhaps you can delete them off your phone to make even more room. Besides, the update will run faster. Let the update run at home on your WiFi and while it is plugged into the phone charger.