FIX 0xa0000400 error during Windows 10 Anniversary Update install

Madalina Dinita
by Madalina Dinita
Managing Editor
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As surprising as this may sound, there are Windows users who still haven’t managed to install Windows 10 on their computers, three days after Microsoft rolled out the update.

Installation errors are still plaguing many users, who are forced to roll back to their previous Windows OS in order to use their machines.

Error 0xA0000400 is one of the most frequent errors users encounter, and it occurs only when they hit the upgrade button.

Error 0xA0000400 stops users from installing the Windows 10

I’m running Windows 10 Education (Build 10240), and when I attempt to manually update to the Anniversary Edition (Build 14393), I get an error code 0xA0000400. The update does not even attempt to install, as soon as I click “update now” it fails immediately with this message.

Microsoft has officially acknowledged the issue but hasn’t offered a fix or a workaround to solve this problem.

It is worth mentioning that the majority of users who reported this issue are running the Windows 10 Education edition.

We’ve written extensively on the Windows 10 installation errors. Check out this guide for more information.

How to fix error 0xA0000400 in Windows 10 install

Although Microsoft hasn’t come up with an official fix for this issue, Windows users have proven once again they are resourceful people and came across a few workarounds.

Solution 1 – Run the troubleshooter

  1. Type troubleshooting in the search bar > select Troubleshooting.
  2. Select View all.
  3. Click on Windows Update > follow the on-screen instructions to run the troubleshooter.

Solution 2 – close all the active apps

“[…] what seems to have worked for me is closing everything I could including Skype, Onedrive, Ventrillo, Blizzard Games Launcher, Curse Updater, Visual Studio 2015, Firefox and Edge.  I have no idea which of these were stopping it, but it is my opinion that it was Skype.  I basically closed as much stuff as I could and it started working.”

The users who tried this workaround confirm that Skype is the culprit.

Solution 2 – turn off the Internet connection when the update download is finished

  1. Go to Windows Update > Check for Updates
  2. Select Learn More > a link will open on your default browser
  3. Click on Get the Anniversary Update now. The folder name is Windows10Upgrade28084 
  4. Open it and make sure it downloads all the files.
  5. Turn off your Internet/WIFI/LAN IMMEDIATELY when download reaches 100%. 

“Since you already have the error, file is already on your computer so it’s going to just verify like a hash check to make sure the Windows 10 update files are intact.Now it should install upgrades but get stuck at the usual 2%, make it stay there for about 30 seconds and re-enable your Internet/WIFI/LAN and the upgrade should finally pass 2%. You can then live in peace.”

Solution 3 – download the Anniversary Update ISO file

You can download it from here for the standard Windows 10 version, and from here for Windows Education.