Update – Note that this didn’t work for me. Still waiting to find a workaround, otherwise I’ll try using an ISO instead

Eagerly waiting for Windows 10 to upgrade my PC.. But nothing was happening. I noticed this error in the Event Viewer System Log:

“Installation Failure: Windows failed to install the following update with error 0x80240020: Upgrade to Windows 10 Pro.”

This thread suggests the cause may be a corrupt download.

The solution (repeated here):

  1. Delete the contents of C:\Windows\SoftwareDistribution\Download
  2. Open an elevated Command Prompt and run wuauclt /updatenow
  3. Go to Control Panel Windows Update and click Check for updates.

After a minute or two, you’ll notice some new files appear in the Download folder, and the Windows Update status will change similar to this:

Downloading Windows 10

I’ll update this post if there’s anything else that requires attention to complete the upgrade successfully.

Later that same day…

Windows Update - Preparing for installation

and even later…

The installation failed with the same error 😢