FIXED – Windows 10 upgrade error “WindowsUpdate_80240020” “WindowsUpdate_dt000”

I was looking forward to upgrade from Windows 7 Professional to the new Windows 10 Pro, but the upgrade didn’t and didn’t come. So I started researching and have found that the upgrade is trying to come, but if fails every time. It failed with a mysterious error message: “WindowsUpdate_80240020” “WindowsUpdate_dt000”.

You can scroll down to see the solution that worked for me.

Upgrade to Windows 10 Pro
Installation date: ?26.?8.?2015 22:43
Installation status: Failed
Error details: Code 80240020
Update type: Important
Install the next version of Windows.
More information: 
http://go.microsoft.com/fwlink/?LinkID=507415
Help and Support: 
http://go.microsoft.com/fwlink/?LinkId=507417

The links go to the normal Windows 10 update page.

So I searched for this error online and the solution I found was this:

Delete all the files in C:\Windows\SoftwareDistribution\Download but not the folder itself.
Open Command prompt with Administrator rights and run “wuauclt.exe /updatenow”.

This made Windows 10 start a download, but after the download finished I still couldn’t install it. The same error was still happening. When I opened the “Get Windows 10” app I got the standard message that I will be notified when ready. I clicked the blue hamburger menu on the top left and selected the first option, “Upgrade for free”. There I clicked the “More information link”. I got a new screen with some useful information.

The detail of the issue was “Your PC is set to log in automatically. After upgrade, you may have issues logging in. Learn more.” The link was pointing to aka.ms/autologon that just redirects to front page of www.microsoft.com. So no help there. It was true that my computer was set to login automatically, so I tried that. I turned off automatic logon and set a password for my account. I restarted my computer, logged off and logged back in but the updates were still failing.

I researched the error 80240020 some more online and have found some old resources from the times of Windows 2000 to what this error means: “Automatic Updates service cannot impersonate the logged-on user to finish downloading and installing the update.” This is a cryptic description, but it led me in the right direction. It turned out that Windows 10 update somehow needs the default “Administrator” account to be active (that was the case for me). Even if my user had administrator rights, that was not enough.

The solution for me was this: Enable “Administrator account”. This is one way of how to do this:

Run Command prompt with administrator rights and run “lusrmgr.msc” (it’s Local users and groups manager).
Click on Users in the left pane, then right click on Administrator in the right pane and select Properties.
Deselect checkbox that says “Account is disabled“.

Log off and when you try to log in you’ll have a new choice, “Administrator”. Choose this choice and a new desktop will be set up for you (if Administrator is a new user on your computer). After some wait you can try to start Windows 10 update again like this:

Open Windows update just so you will see progress later.
Run Command prompt with administrator rights and run “wuauclt.exe /updatenow“. This triggers Windows to check for updates again. The Windows update windows should change to “Downloading…”. If you didn’t delete the folder “C:\Windows\SoftwareDistribution\Download” no actual download will take place because you already have all the files. If you deleted the folder, all 3GB of files will be downloaded again.
After step two a new window should pop up, saying “Your upgrade is ready to install” and will give you two options, “Schedule it for later” and “Start the upgrade now“. There is no “Close”, so you’ll be stuck with this window.

After that, Windows is ready to install, so the wait is finally over.