How to Fix Activation Error 0x803FABB8 on Windows 11 After Upgrading

Some Windows 11 users are suddenly noticing that after upgrading from an older Windows version their installation is no longer activated. Upon attempting to activate it, they get the 0x803FABB8 error code. This problem seems to be exclusive to users upgrading and won’t appear when you’re clean installing Windows 11.

Windows 11 Activation Error 0x803FABB8 after upgrading

After investigating this issue, it turns out that there are 3 different troubleshooting guides that are typically effective in resolving the 0x803FABB8 error when encountered after upgrading to Windows 11:

  • Using the Activation troubleshooter – License key migration has always been a tricky thing inside the Windows ecosystem, so Microsoft developed a utility that’s capable of automatically troubleshooting the most common scenarios that will invalidate the license key during the upgrading process.
  • Contacting Microsoft’s support – As it turns out, there will be scenarios where you won’t be able to resolve the issue on your own, even if your license key is completely valid and compatible with the Windows 11 version that you have installed. In this case, you will need to get in contact with the Microsoft LIVE agent (either in a chat or via calling) and ask them to activate the license remotely.
  • Reinstall Windows 11 – Keep in mind that no license key is compatible with every Windows 11 version. If the license activation fails because the license you have attached to your Microsoft account is not compatible with your currently installed Windows 11 version, the only solution is to install a compatible version.

Run the Activation Troubleshooter

First things first, you should see whether your operating system is capable of resolving the license authentication issue automatically. As some affected users have reported you might be lucky enough to fix the issue automatically by using the Activation Troubleshooter and applying the recommended fix.

Keep in mind that Windows 11 ships with a bunch of automated troubleshooters including one that is equipped with dozens of automated repair strategies related to license activation.

If you haven’t done this already, follow the instructions below to run the Activation troubleshooter and see if you are able to fix the 0x803FABB8 error code:

  1. Press Windows key + I to open up the Settings menu of Windows 11.
  2. Next, click on System from the vertical menu on the left. If the system tab is not visible by default, click on the action icon (top-left corner) to make the vertical menu visible.
    Accessing the System tab
  3. Next, move over to the right-hand side menu, scroll down to the bottom of the screen and click on Activation from the list of available options.
    Click on Activation the System settings
  4. Next, after a brief moment of re-checking your license, Windows 11 will display the error again – when this happens, click on Troubleshoot.

    Running the Activation troubleshooter
  5. Wait until the utility scans your system to figure out if any of the automated strategies are applicable in your particular scenario. If a viable option is found, click on Apply this fix to enforce the recommended fix.
    Applying the recommended fix

    Note: You might also be asked to perform a series of manual steps – in this case, follow the on-screen instructions.

  6. Reboot your PC once the fix is enforced, then reboot and check back to see if your Windows 11 installation is activated after the next startup is complete.

If you already did this and the 0x803FABB8 error is still appearing inside the Activation screen, move down to the next method below.

Reinstall Windows 11 (if applicable)

Keep in mind that you can expect the license activation operation to fail with the 0x803FABB8 if you installed a Windows 11 version that is not compatible with the license key associated with your account.

So for example, if you installed the PRO version of Windows 11 but the license key tied to your account is only for Home versions, you’ll get this error when the activation fails.

If you find yourself in this scenario, the only option at your disposal really is to install a Windows 11 version that is actually compatible with your license key.

In case you’re looking for guidance on how to do this, follow these instructions to clean install Windows 11.

In the event that you have installed a compatible Windows 11 version and the 0x803FABB8 error still occurs, move down to the final potential fix below.

Contact Microsoft

We’ve documented a few user reports where the only resolution in their case was to get in contact with a LIVE Microsoft agent and ask them to activate the license key remotely.

As it turns out, this problem is mostly occurring with the Development builds part of the Insiders Program.

If you find yourself fin this scenario, you have a few options to go about getting in contact with Microsoft:

  1. You can either call the toll-free phone number associated with the region where you’re living in.
  2. You can use the Get Help app to get support.

If you want to go for option 1, here’s a list of official Microsoft toll-free numbers that you can call to receive support.

Toll-free numbers

Additionally, you can use the Get Help app from Microsoft and choose from multiple options.

Open the Get Help app

While the Get Help app is less of a hustle since you won’t be required to remain on the call until a human is assigned to your ticket, it’s generally slower than simply calling the Microsoft Support number in your area.


Kamil Anwar

Kamil is a certified MCITP, CCNA (W), CCNA (S) and a former British Computer Society Member with over 9 years of experience Configuring, Deploying and Managing Switches, Firewalls and Domain Controllers also an old-school still active on FreeNode.