Forcing Windows 10 Upgrade fails with code 80240020

Question

So I was one of the people eager to update from Windows 8.1 to Windows 10 ASAP.

Most of the pages on how to force this update / upgrade provide steps which are the same as the steps on how to resolve this 80240020 issue.

The steps were laid out like this:

1. Navigate to C:\Windows\SoftwareDistribution\Download and delete the contents without deleting the folder itself
2. Open Windows Update from control panel.
3. Run a command prompt (cmd.exe) as Administrator
4. Type command wuauclt.exe /updatenow
5. The windows update should start downloading the upgrade immediately. If not, try to run the command again, or restart the computer and reproduce the steps.

This helped the process to run again, but after the upgrade was downloaded and prepared for installation, it failed later with the mentioned code.

How to resolve this?

Answer 1

For me the solution displayed in question was not helpful, but this fixed it.

Be careful, modifying registry may corrupt your system!

1. Locate the registry key: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade]
2. It should exist, but if not, create it.
3. Create a new DWORD (32-bit) Value with Name = AllowOSUpgrade and set the Value = 0x00000001.
4. Open the Windows Update from Control panel, you should be ready to upgrade immediately.

Afterwards when I did these steps, I was immediately provided with a window to start the upgrade process which went on successfully.