Fix: 0x800f0991 Error Code When Installing KB5036893 Update

The error code 0x800f0991 occurs during the installation of the Windows update KB5036893. When this error occurs, it signifies an issue with the Windows update process, often related to corrupted system files or Windows update files located in the SoftwareDistribution folder. You may also encounter this error if essential Windows services, such as Windows Update or the Background Intelligent Transfer Service (BITS), have stopped running in the background.
This error often results from corrupted files within the SoftwareDistribution folder. The SoftwareDistribution folder stores the temporary files of the Windows Update. When the content in this folder becomes corrupted, Windows often struggles to install the update and shows various error codes, including this 0x800f0991.

Now that we have discussed the crucial causes, let’s explore the solutions to this issue.

1. Reset the Windows Update Component

As stated earlier, the error can be caused by a problem with Windows Update components, such as Windows Update services or files downloaded via the Windows Update utility. By resetting the Windows Update component, you not only restart the stopped Windows Update services but also clear the SoftwareDistribution folder that might contain corrupted files, resulting in this issue.

1. Click here to download the “Windows Update Reset” batch file.
2. After the file is downloaded, locate it in your downloads folder, right-click on the file, and choose Run as administrator from the menu.
3. Wait patiently while the commands are executed in the command prompt.
4. Once the process is complete, your Windows Update components will be reset successfully.

2. Perform an In-place Upgrade

An in-place upgrade involves downloading a Windows ISO file and running it by mounting the file. This process replaces any corrupted components and updates Windows to the latest version. It is highly recommended to perform an in-place upgrade if the issue persists.

1. Go to the official Microsoft site to download the Windows 11 ISO file.
   
2. After downloading, open the ISO file. You can do this by either double-clicking the file or right-clicking it and selecting Mount.
3. In the mounted ISO, run setup.exe and follow the prompts. Wait for Windows to restart.
   
4. Once the process is complete, the error message should be resolved.

3. Download the Windows Update Manually

We can also manually download a Windows update if it fails to install due to issues with the Windows Update component or other reasons.

Downloading the Windows update manually is one of the straightforward ways to resolve any Windows update error.

1. To manually download a Windows update, go to the Microsoft Update Catalog. This site allows you to download any Windows update that has been released.
2. Once you’re on the Microsoft Update Catalog website, use the search bar to look for the update by entering KB5036893.
3. When you find the correct update, click the Download button next to it. A new window will appear—double-click the link shown in that window to begin the download.
4. Once the download completes, locate the file and double-click it to start installing the update.

4. Run SFC and DISM Commands

Running the SFC (System File Checker) and DISM commands can help resolve the error 0x800f0991 by repairing corrupted files. SFC is a command-line utility that repairs system files, including DLL and executable files. Meanwhile, DISM goes a step further and fixes deeper issues within the system, including the Windows Update component.

1. Press the Win key and type Command Prompt.
2. Right-click on Command Prompt and choose Run as administrator.
3. In the Command Prompt window, type and run the following commands, one at a time:

   sfc /scannow DISM /Online /Cleanup-Image /RestoreHealth

   

4. After the commands finish running, check if the error still exists.

Windows update errors can also occur due to insufficient space on the system drive. By performing a disk cleanup, you not only remove corrupted temporary and cache files but also free up space for the upcoming Windows updates. So if you don’t have enough space, you can try running the disk cleanup utility by following the steps in the linked article.