How to fix
Windows activation error 0x803FABB8
on Windows

Hi, I had some issues with my PC constantly crashing, so I decided to reinstall. While my crashes were now gone, I noticed that my Windows is no longer activated, and the message says there's an activation issue - error code 0x803FABB8. I am not sure how to go about this because I did use genuine Windows before, which I got as a free upgrade back with Windows 10 release. I have no clue what my key is or how to retrieve it. Any help would be appreciated.

Microsoft has released many versions of its ever-improving operating system Windows, some of which were loved by users, while others having a relatively negative reception - Windows Vista is one of the best such examples. Technically, all the operating systems can still be run if the user really wants to, although it is highly advised against by the software developers.

Unsupported systems, such as Windows 7 or XP, might result in serious security issues, as they are unable to receive the most recent updates to patch software vulnerabilities. Besides, each of the new Windows versions brings in major bug fixes, new features, UI[ref en-1] iterations, and overall quality of life improvements across the board.

Therefore, the need for system upgrades is always something many users are keen on doing - a process that sometimes might be stopped by errors such as 0x803FABB8. While some errors stop the upgrade process completely, this particular error only shows up within the Activation section of the Settings panel and reads as follows:

We can't activate Windows on this device right now. You can try activating again later or go to the Store to buy genuine Windows. Error code: 0x803FABB8

The error message implies that the license for the operating system is not valid or that the Windows was installed illegally. However, the problem persists for those who do have a valid license and acquired it either by purchasing the OS or when they received it as a free upgrade for Windows 10.

The problem is that the digital license is not being correctly recognized, and the error 0x803FABB8 fix can be performed via several methods. Keep in mind that some of these solutions might not work for you. Likewise, if you are running an illegitimate version of the operating system, none of the methods will work.

OS activation issues became especially prominent when they tried to use a free upgrade back in 2015 when Windows 10 was released. In fact, we have previously discussed such problems in our articles for 0x8007267C, 0xC004F213, 0xC004F074, and many others.

With Windows 11 release,[ref en-3] many users were eager to try the new operating system (they need to meet certain system requirements) and seems that they encountered the same problem. Regardless of which operating system you are using, we recommend you first check it with a powerful PC repair tool [d1] to ensure that there are no underlying issues, such as malware[ref en-2] infection, that could be causing the error.

1. Run the troubleshooter

If you haven't done so already, you should run the troubleshooter for the error.

• Right-click on Start and select Settings
• Go to the Update & Security section
• Select Activation on the left
• Under the error code, click Troubleshoot

  

• Wait till the troubleshooter scans your computer and provides you with a solution.

At this point, many people receive the "Unable to activate Windows." If that is the case, proceed with the solutions below.

2. Install all the updates for Windows

Inability to upgrade correctly could be caused by incorrectly installed or corrupted Windows updates. Applying all the latest updates could help you fix this issue:

• Type Updates in Windows search and hit Enter
• On the right side, click Check for updates
• Wait till all the data is downloaded and installed, and don't forget to install all the optional updates
• After it's done, reboot the computer

  

• Try upgrading to the newest version again.

3. Activate via Command Prompt

If you are using a digital license, proceed with the following:

• Type cmd in Windows search
• Right-click on Command Prompt and select Run as administrator
• When User Account Control shows up, click Yes
• Once Command Prompt opens, copy and paste the following command:
  slmgr /xpr
• Press Enter.

  

If you are using a product key, use the following instructions:

• Open  Command Prompt as administrator once again and use the following command:
  wmic path softwarelicensingservice get OA3xOriginalProductKey
• Paste the slmgr.vbs.ipk <product key> into the window, and press Enter
• Finally, use slmgr.vbs/ato command and hit Enter
• Restart your PC and see if your Windows is activated.

4. Activate via phone

You can also activate Windows via your local phone line. Use this option if none of the above helped you.

• Press Win + R and type Slui 4, press Enter
• In the new window, select your country and press Next
• This should provide you with a local support number
• Pick up your phone and call it - follow the automated instructions.

  

Note: you might need to provide some information about your Windows license. To acquire it, open Command Prompt as administrator and type in slmgr.vbs /dlv command and hit Enter - it should show you more details you might need while on the call.