Upgrading windows 10 home to pro

I upgraded my desktop PC from windows 7 home to windows 10 home 1511. Everything went well and windows 10 home is running fine. Now I would like to upgrade to windows 10 pro. I have a valid windows 7 ultimate key.

I found a post that explained how to upgrade to windows 10 pro from home. It advised to change the product key to
VK7JG-NPHTM-C97JM-9MPGT-3V66T which will initiate the upgrade then, after the upgrade is complete, change the key to the windows 7 ultimate key to active.

I changed the product key to VK7JG-NPHTM-C97JM-9MPGT-3V66T, which gave me the UPGRADE button. Upon clicking the upgrade option a download begins. Once it reaches 100% the computer reboots.

When the computer restarts I am still on windows 10 home and nothing else happens. It still shows ACTIVATED for windows 10 home.

What can I do to continue the upgrade? I have tried the above process 3x with the same results.

There are no error messages that appear.

Guidance appreciated.

Thank you

Hmmm..... the first thing I would try is a complete disk cleanup using option 2 here:
Disk Cleanup - Open and Use in Windows 10 - Windows 10 Forums

FYI - By disabling Avast Antivirus I was able to complete the upgrade.

Avast has caused a lot of problems for a lot of people. I would just uninstall it