Windows 10 upgrade failure, previous version of Windows restored - Troubleshooting / Possible Fix

"Your upgrade is ready to install" was the notification I received on my Windows 7 on 29th of July afternoon. Excited, I clicked the begin installation button and followed the instructions on the screen, I stayed glued to my computer making sure I miss not even a single message on the screen.

My windows upgrade advanced until 30% completion without much difficulty. After that, the setup required an automatic computer restart. It restarted normally but after that it was not able to continue with the update. I could momentarily see flashes of screen that read something like "attempting to resume the Windows installation...", but it never could show up the same 30% installed screen after that point. Eventually after few more attempts it auto-restarted and this time it read, "Restoring your previous version of windows".

The Windows 7 that I had earlier was restored (without any issues); it was disappointing at that moment but I was also relieved with the fact that I did not have to loose my running system.

I re-tried the installation twice same day without success. I again attempted the installation next day using the Media creation tool’s bootable USB that Microsoft has offered. That didn't help much. The computer would go no further than the 30% bar and restart to have Windows 7 restored again and again.

This afternoon I did some else before I again hit that installation button, and it changed the whole scenario. My laptop is: HP Pavilion dv3, I have Windows 7 Ultimate installed on c-drive [C:] and therefore I did the following steps on my machine:

1. Deleted everything inside the Windows update download folder: [C:\Windows\SoftwareDistribution\Download]
2. Disabled my antivirus
3. Executed the Window’s Disk Clean Utility to clean [C:]
4. Disk defragmented [C:]
5. Scheduled the Window’s Disk Check Utility with 'Automatically fix errors + repair drives' options (both ticks) and restarted the system.

After doing them all, I started the Setup.exe from the flash drive I had created earlier from within the running Windows 7 file explorer. This time, it was not disrupted and made through that 30% kink, the installation completed smoothly. Finally I could see the fully functional activated Windows 10 running on my system. Oh I was happy!

I don’t know if it works for all or not but still thought of sharing this information; if it can help someone out there. No harm in giving it a try if you are having the same issues with installation.

Good luck!