How to fix
Windows update error 0x800f0801
on Windows

Windows failed to install the latest update with error code 0x800f0801. After this, the message says that important updates are missing. How can I fix this? I tried installing it again but to no avail.

The error 0x800f0801 is one of the common problems experienced during an update in Windows operating systems. Normally, this error does not allow one to install updates, which disruptively results in not receiving vital security patches and operating system improvements. This error is tagged with CBS_E_NOT_APPLICABLE code proof that some of the update files or components are either missing or incompatible or corrupted since the update was successfully applied.

The symptoms of error code 0x800f0801, as a rule, include failed attempts to install updates. The system may display the message: "There were problems installing some updates, but we'll try again later."

Besides this, you may also experience your system being unable to go on with the update installation and simply bails on the update process. This may lead to performance conditions or may weaken the system towards certain security conditions in case of some critical updates remain installed.

This error most frequently occurs when a file required by the update - a system file - is broken or missing. It can also be caused by a conflict with third-party software, such as antivirus, or corruption within the Windows Update service.

Sometimes, the error concerns issues of the Component-Based Servicing (CBS) stack, which installs, modifies, and removes Windows updates. When this stack is broken or lacks required components, this can completely prevent the update process from happening.

Error 0x800f0801 not only occurs after an incomplete or interrupted update installation, but it can also be witnessed in systems that have not been well maintained. This includes systems with outdated drivers or an older version of Windows operating systems that are causing a clash with the new update. Moreover, system file corruption and hardware compatibility can also create this error.

The solution to the 0x800f0801 error involves fixing some issues related to update files, system components, or software conflicts. More serious cases will bring in a PC repair tool, such as [d1], which is capable of finding deeper system problems and fixing them automatically. 

If you decide to proceed with manual solutions, make sure you have already tried the following:

• Restart your computer if you haven't yet.
• Ensure that the time and date are set correctly.
• Scan your computer for malware infections.
• Temporarily disable third-party antivirus and try updating again.

Fix 1. Repair corrupted files

• Type cmd in the Windows search box.
• Right-click on Command Prompt and select Run as administrator.
• When UAC asks you whether you want to make changes, agree by pressing Yes.
• Next, copy and paste the following commands, pressing Enter each time:
  sfc /scannow
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth
  (Note: if you get an error executing the last command, add /Source:C:\RepairSource\Windows /LimitAccess to it and try again.)
  
• Restart your system.

Fix 2. Perform Disk Cleanup

• Type Disk Cleanup in Windows search and hit Enter.
• If your Windows is installed on drive C, pick it from the list (it should be by default) and press OK.
• Click Clean up system files.
• Select your main disk again and click OK.
• Here, select the largest portions of the data used - these typically include Temporary Internet Files, Windows Update, Temporary Files, Recycle Bin, Delivery Optimization Files, and others.
• Click OK - the process should be finished shortly.

Fix 3. Check services responsible for Windows update process

• Type in Services in Windows search and hit Enter.
• Locate Windows Update service.
• If this service is already running, right-click and select Restart.
• If it is not running, double-click it, select Automatic under the Startup type from the drop-down menu.
• Click Start, Apply, and OK.
• Repeat the process with the Background Intelligent Transfer Service (BITS), Cryptographic, and Windows Installer services.

Fix 4. Run Windows update troubleshooter

• Type Troubleshoot in Windows search and press Enter.
• Select Additional troubleshooters/Other troubleshooters.
• Find Windows Update from the list.
• Click it and select Run the troubleshooter/Run.
• Restart your system when the update process finishes.

Fix 5. Install the update manually

• Type in Updates in Windows search and press Enter.
• Select View update history.
• Find the update that failed with the 0x800B0003 error and copy its KB number.
• Open your browser and go to Microsoft Update Catalog.
• Within the search bar, type in the KB number and clicks Search.
• Find the correct version of the update for your operating system (to check this, right-click on Start and pick System. Under Device specifications and check the System type) and click Download.
• Use on-screen guidelines to finish the installation process and restart your PC.

Fix 6. Use Media Creation Tool

• Visit the official Microsoft website and download Windows 10 installation media (Windows 11 version).
• Double-click the installer, select Yes when UAC shows up, and agree to the terms.
• Select Upgrade this PC now and click Next.
• Windows will start downloading the needed files.
• Agree to the terms once again and click Next.
• Before installing, make sure that you are happy with your choices (otherwise, you can click Change what to keep option).
• Finally, click Install to begin the upgrade process.

Fix 7. Reset Windows update components

• Type cmd in Windows search.
• Right-click on Command Prompt and select Run as administrator.
• When the User Account Control window pops up, click Yes.
• Type the following commands one by one in Command Prompt and press Enter after each:
  net stop wuauserv
  net stop cryptSvc
  net stop bits
  net stop msiserver
  Ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
  Ren C:\Windows\System32\catroot2 Catroot2.old
• When these commands are executed, the last thing to do is to re-enable relevant services:
  net start wuauserv
  net start cryptSvc
  net start bits
  net start msiserver
• Reboot your device.