How to fix
Windows update error 0x80040155
on Windows

Hello. How can I install the latest Windows update if it keeps failing for me all the time? I have been trying for weeks and I keep running into an error 0x80040155. Any tips for this? I have never run into such an issue before so I'm not sure what to do next.

Windows updates are essential as they consistently introduce exciting new features, fix both major and minor bugs, enhance performance, and patch software vulnerabilities. Thus, it's vital to always keep your Windows version up to date. However, an error such as 0x80040155 can sometimes prevent you from doing so.

Microsoft typically delivers updates on Patch Tuesday, which occurs once a month. These updates are normally installed automatically, but depending on your user preferences, you may need to start the process manually using the settings menu or another manner.

During the update process, Microsoft's servers are contacted via the internet connection to download the latest patch files, which are then installed on your device. If anything goes wrong during this procedure, it will fail with an error code. Usually, this can be caused by an unstable internet connection, general bugs, or server problems and tends to resolve itself within a day or two, so users usually aren't too concerned.

However, the 0x80040155 error code might persist, preventing you from accessing the latest security patches, stability improvements, and new features, which can be quite frustrating. Fortunately, in most cases, this issue can be resolved with a bit of troubleshooting or by using automatic tools like [d1]. We highly recommend trying this before proceeding with the manual steps outlined below.

Fix 1. Run Windows Update troubleshooter

The Windows Update troubleshooter is designed to automatically detect and fix common problems with the Windows Update process. It can resolve issues that prevent updates from installing properly.

• Type in Troubleshoot in Windows search and hit Enter.
• Select Additional Troubleshooters/Other troubleshooters option.
• Locate Windows Update and click Run/Run the troubleshooter.
• As soon as the scan finishes, apply the recommended fixes.

Fix 2. Check relevant services

Certain Windows services must be running for updates to install correctly. Ensuring these services are enabled can help resolve update issues.

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

Fix 3. Repair corrupted files

SFC and DISM can repair corrupted system files that might be preventing updates from installing.

• Type in cmd in Windows search.
• Right-click the Command Prompt result and pick Run as administrator.
• User Account Control will ask whether you want to allow changes - click Yes.
• Type this command and press Enter:
  sfc /scannow
• Wait for the scan to finish.
• Then, use the following commands, pressing Enter after each:
  Dism /Online /Cleanup-Image /CheckHealth
  Dism /Online /Cleanup-Image /ScanHealth
  Dism /Online /Cleanup-Image /RestoreHealth
• Restart your computer.

Fix 4. Perform Disk Cleanup

Disk Cleanup helps to remove temporary files and free up space, which can resolve issues with installing updates.

• Type Disk Cleanup in Windows search and hit Enter
• If your Windows is installed on drive C, pick it from the list (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 and wait for the cleanup process to finish.

Fix 5. Install the update manually

Manually downloading and installing the update can bypass issues with the automated update process.

• Type in Updates in Windows search and press Enter.
• Select View update history.
• Find the update that failed with the 0x80040155 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 system.

Fix 6. Reset Windows update components

Resetting the Windows Update components can fix corruption within the update process itself.

• Open Command Prompt as administrator, as explained previously.
• In the new window, use the following commands, pressing Enter after each:
  net stop bits
  net stop wuauserv
  net stop appidsvc
  net stop cryptsvc
  Del “%ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\*.*”
  rmdir %systemroot%\SoftwareDistribution /S /Q
  rmdir %systemroot%\system32\catroot2 /S /Q
  regsvr32.exe /s atl.dll
  regsvr32.exe /s urlmon.dll
  regsvr32.exe /s mshtml.dll
  netsh winsock reset
  netsh winsock reset proxy
  net start bits
  net start wuauserv
  net start appidsvc
  net start cryptsvc 
• Restart your system.

Fix 7. Perform Clean Boot

A clean boot starts Windows with a minimal set of drivers and startup programs, which can help identify if background programs are interfering with updates.

• Type msconfig in the Windows search box and press Enter.
• Select the Services tab and tick the Hide all Microsoft services checkbox at the bottom.
• Pick Disable all.
• Go to the Startup tab and click Open Task Manager.
• Here, right-click on each of the non-Windows entries and select Disable.
• Close down the Task Manager.
• Go to the Boot tab and tick the Safe boot option
• Reboot your computer and try updating it again.

Fix 8. Use Media Creation Tool

The Media Creation Tool allows you to perform an in-place upgrade, which can resolve persistent update issues.

• Visit the official Microsoft website and download Windows 10 installation media (Windows 11 version)
• Double-click the installer and select Yes when UAC shows up
• Agree to terms
• Select Upgrade this PC now and select Next
• Windows will now download all the necessary files – it might take awhile
• Agree to 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)
• Click Install to begin the upgrade process.