KB5087420 not installing or stuck in Windows 11
- Windows 11, version 23H2
- OS Build 22631.7079
Daniel Okafor5 min readQuick answer
If KB5087420 fails to install or gets stuck during download, first run the built-in Windows Update troubleshooter in Settings. If that does not resolve the issue, clear the temporary update cache inside the SoftwareDistribution folder using Command Prompt. Finally, run the DISM and SFC repair tools to fix any corrupted system files preventing the update from completing.
Released on May 12, 2026, cumulative update KB5087420 brings Windows 11, version 23H2 to OS Build 22631.7079. This package contains critical security patches and system improvements designed to keep your machine running smoothly. However, many users report that the update process can freeze at specific percentages such as 0%, 20%, or 99%, or fail outright with vague error messages during the reboot process.
When Windows Update gets stuck or repeatedly fails to apply KB5087420, it is usually caused by corrupted temporary download files, interrupted background services, or damaged system components. Fortunately, you do not need to be a technical expert to resolve this issue. Below are four reliable methods to get your update installation back on track, ordered from the simplest to the most advanced.
Method 1: Run the Windows Update troubleshooter
Illustration: the Troubleshoot > Other troubleshooters page under Settings > System
Use this method first whenever a monthly update gets stuck downloading or fails with a generic error message. Windows includes an automated diagnostic tool designed specifically to detect and resolve stuck update services and common background glitches.
- Click the Start button on your taskbar and select Settings (represented by the gear icon).
- In the left menu panel, make sure System is selected, then scroll down on the right pane and click Troubleshoot.
- Click Other troubleshooters to view the list of automated repair tools available on your system.
- Locate Windows Update near the top of the list and click the Run button next to it.
- Wait while the screen shows "Detecting problems" and follow any on-screen prompts if the tool asks for permission to apply a fix.
What to expect afterwards: The troubleshooter will check your background services and clear minor cache bottlenecks. Once complete, return to Settings, select Windows Update, and click Check for updates to retry installing KB5087420.
Method 2: Clear the SoftwareDistribution cache folder
Illustration: the Windows Update page in Windows 11 Settings
Use this method if KB5087420 stops responding at a specific download percentage or if your system attempts to install broken download files repeatedly. The SoftwareDistribution folder stores temporary update files, and clearing it forces Windows to download a fresh copy of the update package.
Warning: Stopping update services and clearing cache folders temporarily resets your download progress, but it will not erase your personal files or installed programs.
- Click the Start button, type "cmd" into the search bar, right-click Command Prompt in the results list, and select Run as administrator.
- In the Command Prompt window, type
net stop wuauservand press Enter to pause the main update service. - Type
net stop bitsand press Enter to halt the background transfer service. - Press Windows Key + R on your keyboard to open the Run box, type
C:\Windows\SoftwareDistribution, and click OK. - Press Ctrl + A to select all files and folders inside this directory, right-click any highlighted item, and select Delete.
- Switch back to your administrator Command Prompt window, type
net start wuauservand press Enter, then typenet start bitsand press Enter to restart the services.
What to expect afterwards: Windows Update will automatically recreate the deleted subfolders and download a clean, uncorrupted copy of KB5087420 when you check for updates again.
Method 3: Repair damaged system files with DISM and SFC
Use this method if the update reaches the installation stage but fails during reboot, indicating that essential Windows core files might be corrupted or missing.
Warning: DISM and System File Checker scan and replace system files in your Windows installation. While safe, this process makes direct modifications to core system components to repair corruption.
- Click the Start button, type "cmd", right-click Command Prompt, and choose Run as administrator.
- Type
DISM.exe /Online /Cleanup-image /Restorehealthand press Enter. - Wait for the operation to reach 100%. The screen will display "The restore operation completed successfully."
- Type
sfc /scannowand press Enter to initiate the system file verification scan. - Wait for the scan to finish. The screen will report whether it found corrupt files and successfully repaired them.
- Restart your computer when the commands complete.
What to expect afterwards: Corrupted system files required for patching will be restored to their default state, allowing KB5087420 to integrate smoothly.
Method 4: Manually reset Windows Update components
Use this advanced method if temporary files remain locked or if background database corruption stops Windows Update from connecting properly to Microsoft servers.
- Click Start, type "cmd", right-click Command Prompt, and select Run as administrator.
- Stop all related services by executing these four commands one by one (press Enter after each):
net stop wuauserv,net stop cryptSvc,net stop bits, andnet stop msiserver. - Rename the main update catalog folders by entering
ren C:\Windows\SoftwareDistribution SoftwareDistribution.oldand pressing Enter, then enteringren C:\Windows\System32\catroot2 catroot2.oldand pressing Enter. - Restart the services by executing
net start wuauserv,net start cryptSvc,net start bits, andnet start msiserver. - Close Command Prompt and restart your PC.
What to expect afterwards: Windows will completely rebuild its update databases from scratch, clearing away deep-seated update installation blocks.
If nothing worked
If KB5087420 still refuses to install after running these fixes, there are a few final steps you can take. First, make sure your system drive has at least 20 GB of free space, as update installations require ample temporary storage to extract files. Next, check if third-party antivirus software or active VPN connections are interfering with the download process; temporarily disabling them can often allow the patch to complete.
Alternatively, you can temporarily pause updates by opening Settings, navigating to Windows Update, and selecting Pause for 1 week. This gives Microsoft time to address potential server-side glitches or release a revised installer. If you need the update immediately for security compliance, consider using Windows 11 installation media to run an in-place repair upgrade, which refreshes your system files to OS Build 22631.7079 while keeping all apps and personal data intact.
Sources
Frequently asked questions
What is update KB5087420?
KB5087420 is a cumulative update released on May 12, 2026, for Windows 11, version 23H2. It updates your operating system build to OS Build 22631.7079 and includes key security patches and reliability fixes.
Why does KB5087420 get stuck downloading at 99%?
Updates usually freeze at 99% when temporary files in the SoftwareDistribution folder become corrupted or when background services stall while extracting patch packages. Clearing the update cache forces Windows to download a clean file.
Is it safe to clear the SoftwareDistribution folder in Windows 11?
Yes, clearing the SoftwareDistribution folder is completely safe. Windows automatically rebuilds the folder and downloads fresh updates the next time you run Windows Update.
Checked against Microsoft's release notes on ; re-checked when a new build ships.
Writes Thea's error-code and app-breakage guides. Each fix is checked against Microsoft's documentation and community reports, and updated when a new Windows 11 build changes the steps.
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