Fix Windows KB5004945 Update Error – Windows 10, Windows 11 2026

Understanding KB5004945 Update Installation Issues

KB5004945 represents a critical Windows security and feature update that occasionally encounters installation failures across Windows 10 and Windows 11 systems. This comprehensive troubleshooting guide addresses the most common causes and provides proven solutions used by system administrators worldwide.

Quick Fix Summary

Run Windows Update Troubleshooter from Settings → Update & Security → Troubleshoot, then execute sfc /scannow in Command Prompt as administrator to repair corrupted system files preventing KB5004945 installation.

Symptoms of KB5004945 Installation Failure

• KB5004945 update fails to install with generic error messages
• Windows Update shows 'Installation failed' or 'Download failed' status
• System restarts but update rollback occurs automatically
• Error codes 0x80070005, 0x800f0922, or 0x80240034 appear during installation
• Windows Update service becomes unresponsive or crashes
• System performance degradation after failed installation attempts

Root Causes of the Problem

• Corrupted Windows Update components or system files
• Insufficient disk space on system drive (less than 10GB free)
• Third-party antivirus software blocking update installation
• Windows Update service dependencies not running properly
• Registry corruption affecting update mechanisms
• Conflicting pending updates or incomplete previous installations
• Group Policy restrictions preventing automatic updates

Solution Methods

Method 1: Run Windows Update Troubleshooter and SFC Scan

Start with the built-in troubleshooter to automatically detect and fix common update issues:

1. Press Windows + I to open Settings
2. Navigate to Update & Security → Troubleshoot → Additional troubleshooters
3. Click Windows Update and select Run the troubleshooter
4. Follow the on-screen prompts and apply any recommended fixes
5. After completion, open Command Prompt as administrator
6. Run the System File Checker scan:

sfc /scannow

Wait for the scan to complete (typically 15-30 minutes). If corrupted files are found and repaired, restart your computer.

Verification: Go to Settings → Update & Security → Windows Update and click Check for updates. KB5004945 should now install successfully.

Method 2: Reset Windows Update Components

Manually reset all Windows Update services and clear the update cache:

1. Open Command Prompt as administrator
2. Stop Windows Update services:

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver

3. Rename the SoftwareDistribution and catroot2 folders:

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old

4. Restart the Windows Update services:

net start wuauserv
net start cryptSvc
net start bits
net start msiserver

5. Clear the Windows Update cache completely:

dism /online /cleanup-image /startcomponentcleanup

Verification: Restart your computer and check Windows Update. The KB5004945 update should appear and install without errors.

Method 3: Use DISM Tool to Repair Windows Image

Repair the Windows system image using the Deployment Image Servicing and Management tool:

1. Open Command Prompt as administrator
2. Check the current image health:

dism /online /cleanup-image /checkhealth

3. Scan for component store corruption:

dism /online /cleanup-image /scanhealth

4. If corruption is detected, repair the image:

dism /online /cleanup-image /restorehealth

5. After DISM completes successfully, run SFC again:

sfc /scannow

6. Clear the Windows Update cache:

wsreset.exe

Verification: Restart the system and attempt to install KB5004945 through Windows Update. The update should now proceed without component-related errors.

Method 4: Manual Download and Installation

Download and install KB5004945 manually when automatic installation fails:

1. Visit the Microsoft Update Catalog website
2. Search for "KB5004945" in the search box
3. Identify the correct version for your system architecture (x64, x86, or ARM64)
4. Download the appropriate .msu file to your Downloads folder
5. Before installation, ensure sufficient disk space (at least 10GB free)
6. Right-click the downloaded .msu file and select Install
7. Alternatively, install via Command Prompt:

wusa.exe "C:\Users\%USERNAME%\Downloads\windows10.0-kb5004945-x64.msu" /quiet /norestart

8. Monitor the installation progress in the Command Prompt window
9. If installation fails, try the standalone installer method:

dism /online /add-package /packagepath:"C:\Users\%USERNAME%\Downloads\windows10.0-kb5004945-x64.msu"

Verification: Check installed updates in Settings → Update & Security → View update history. KB5004945 should appear in the successfully installed updates list.

Method 5: Registry Cleanup and Advanced Troubleshooting

Perform advanced registry cleanup and service configuration when other methods fail:

1. Create a system restore point before proceeding
2. Open Registry Editor (regedit.exe) as administrator
3. Navigate to the Windows Update registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate

4. Delete the following subkeys if they exist:

• Auto Update
• RebootRequired
• PostRebootReporting

5. Navigate to the AU registry location:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update

6. Delete the entire Auto Update key if present
7. Reset Windows Update Agent using PowerShell:

Get-Service -Name wuauserv | Stop-Service -Force
Remove-Item -Path "C:\Windows\SoftwareDistribution" -Recurse -Force
Get-Service -Name wuauserv | Start-Service

8. Re-register Windows Update DLL files:

regsvr32 /s atl.dll
regsvr32 /s urlmon.dll
regsvr32 /s mshtml.dll
regsvr32 /s shdocvw.dll
regsvr32 /s browseui.dll
regsvr32 /s jscript.dll
regsvr32 /s vbscript.dll
regsvr32 /s scrrun.dll
regsvr32 /s msxml.dll
regsvr32 /s msxml3.dll
regsvr32 /s msxml6.dll
regsvr32 /s actxprxy.dll
regsvr32 /s softpub.dll
regsvr32 /s wintrust.dll
regsvr32 /s dssenh.dll
regsvr32 /s rsaenh.dll
regsvr32 /s gpkcsp.dll
regsvr32 /s sccbase.dll
regsvr32 /s slbcsp.dll
regsvr32 /s cryptdlg.dll

Verification: Restart the computer and run Windows Update. KB5004945 should install successfully after the comprehensive cleanup and re-registration process.

Verification Steps

To confirm KB5004945 has been successfully installed:

1. Open Settings → Update & Security → Windows Update
2. Click View update history and verify KB5004945 appears in the list
3. Run the following PowerShell command to check installed updates:

Get-HotFix | Where-Object {$_.HotFixID -eq "KB5004945"}

If the command returns update details including installation date, the update is successfully installed. Additionally, check system stability by running sfc /verifyonly to ensure no new corruption was introduced.

Advanced Troubleshooting

If KB5004945 still fails to install after trying all methods above, consider these advanced alternatives:

• Clean Boot Installation: Restart in clean boot mode to eliminate third-party software conflicts. Run msconfig, select Selective startup, and disable all startup items and non-Microsoft services.
• Windows Update Medic Service: Ensure the Windows Update Medic Service is running by executing sc config WaaSMedicSvc start=auto and sc start WaaSMedicSvc in Command Prompt.
• Group Policy Reset: If domain-joined, check Group Policy restrictions by running gpupdate /force and reviewing Windows Update policies in gpedit.msc.
• System File Replacement: For persistent corruption, consider using sfc /scannow from Windows Recovery Environment or performing an in-place upgrade installation.
• Windows Update Assistant: Download and run the Windows 10/11 Update Assistant tool directly from Microsoft to force the update installation.

If none of these solutions work, the issue may require a complete Windows reset or professional technical support, as it could indicate deeper system corruption or hardware-related problems.