Installation Failure: Windows failed to install the following update with error 0x800F0986: Security Update for Windows (KB4483235).

Hi,

My name is Angel. I am an Independent Advisor. Thank you for posting in Microsoft Community.

I would suggest you to follow these methods:

Method 1.
Run the Windows Update troubleshooter

1.Download the Windows Update Troubleshooter, and then select Open or Save in the pop-up window:
https://aka.ms/wudiag

Notes
• If the pop-up doesn’t come up, you might have a pop-up blocker on. If you’re using Microsoft Edge, instructions for disabling the pop-up blocker are here. For Internet Explorer, instructions are here. If you are using a different browser or separate pop-up blocker, check the website of the browser or blocker’s manufacturer.
• If you select Save, you need to go to the folder where the troubleshooter is downloaded to after the download is complete, and then double-click the latest wu.diagcab file to run the troubleshooter.

2.Select Next and follow the steps in the wizard to find and fix problems with Windows Update .

Method 2.

Download the most recent Servicing Stack Update (SSU)

Determine whether you are using 32-bit or 64-bit Windows:
1. From Start, choose Settings.
2. Select System.
3. Click About.
4. Scroll down to System type.
Download the version of the latest SSU (KB4456655) that matches your version of Windows from the Microsoft Update Catalog.
Restart your device and check for updates.
Did this resolve the issue?


Method 3.

Download the most recent KB

1. Go to the Update history page. https://support.microsoft.com/help/12387/window...
2. Find the most recent update KB for the version of Windows 10 you have – it’s usually at the top of the list – and either write the KB number down or copy it.
3. Go to the Microsoft Update site and search for the KB number. http://catalog.update.microsoft.com/v7/site/Hom...
4. Select the link for the download, and then choose Download. Select Save if you are prompted.
5. When the download completes, select Open to start the update.


Method 4.

Fix Windows file corruption

Important
You need to run both the DISM and SFC commands shown below, not just one of them.
1. Open an elevated command prompt. To do this, right click the Windows button, and then select Command Prompt (Admin). If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Yes.
2. Type the following command, and then press Enter.
DISM.exe /Online /Cleanup-image /Restorehealth
Note It might take several minutes for the command operation to be completed.
3. Type the following command and press Enter.
sfc /scannow
Note It might take several minutes for the command operation to be completed.
4. Close the command prompt, and then run Windows Update again.


Method 5.
Perform an in-place upgrade

Download the Windows 10 Media Creation Tool (MCT) https://www.microsoft.com/software-download/win... and use it to perform an “in-place upgrade” of Windows 10. We have a video that can show you how if you aren’t sure. https://aka.ms/W10CleanInstall

Source:

https://support.microsoft.com/en-us/help/10164/...



Hope the information provided is useful. If the issue persists, reply here and we will be glad to help you.

Angel.