May I ask if you uninstalled your McAfee Subscription, or at least disabled it before upgrading. It is recommended to always do so before any major upgrade such as a Service Pack/OS. Also is the Windows 10 you have installed the ( final release ) RTM, or the Preview/Developer Version? See: Windows 10 Forums
It could be that during the upgrade, your McAfee subscription could quite possibly became corrupt. You can try doing a Clean Uninstall/Reinstall by following these Guidelines/Instructions: How to uninstall or re-install supported McAfee products using the Consumer Products Removal tool I might add that when re-installing, use Internet Explorer 11 as it is part of Windows 10 as well.
Or if you feel you need assistance, can contact Technical Support 24/7 via Phone/or Online Chat being much quicker. Services and Support for Home and Office
All the Best
Thanks Peter Good Idea.