I had Windows 7 Professional running on a system and I downloaded the “Free” upgrade to Windows 10. The installer downloaded quickly and the initial checks went pretty quickly. Then it began checking for updates and Hung for over an hour.
So I restarted the process and it repeated the same issue. I looked online and found the following:
Windows Update Troubleshooter:
I did not stop the update process of Windows 10. I just ran that repair tool in the background and then Windows 10 quickly finished the updates and was ready to install!
In some cases a quick fix is to temporarily stop the Windows update service.