KB5079391 not installing or stuck in Windows 11
- Windows 11, version 24H2
- Windows 11, version 25H2
- OS Build 26100.8116
- OS Build 26200.8116
Maya Reyes4 min readQuick answer
KB5079391 is an optional preview update for Windows 11 versions 24H2 and 25H2 (OS Builds 26100.8116 and 26200.8116). If the installation gets stuck, freezes downloading, or fails to complete, you can resolve the issue by running the Windows Update troubleshooter, resetting update cache components, or executing DISM and SFC system repairs.
Microsoft released KB5079391 on March 26, 2026, as an optional preview cumulative update for devices running Windows 11 version 24H2 and version 25H2. Installing this update advances your operating system build to OS Build 26100.8116 or OS Build 26200.8116 depending on the base version running on your machine. As an optional preview release, KB5079391 delivers early access to non-security fixes, system quality refinements, and background OS improvements scheduled for upcoming general releases.
However, a number of users encounter issues when attempting to apply this update. Common symptoms include Windows Update hanging indefinitely at specific download percentages (such as 0%, 20%, or 99%), installation error prompts appearing during reboot, or automatic rollbacks where Windows reverts changes upon restarting. Because preview updates rely on clean system component stores and active update services, local cache corruption or broken update components are usually responsible for these installation stalls.
Method 1: Run the Windows Update troubleshooter
Illustration: the Troubleshoot > Other troubleshooters page under Settings > System
- Open the Start menu and select Settings (or press Windows Key + I).
- Under the System tab in the left sidebar, scroll down the right pane and click Troubleshoot.
- Click Other troubleshooters to display the available diagnostic tools.
- Locate Windows Update near the top of the list and click the Run button next to it.
- Allow the diagnostic tool to scan for hanging update queues, missing service triggers, or corrupt configurations. If prompted, click Apply this fix.
When to use: Use this built-in utility as your first fix whenever an update stalls during download or throws an initial error code. After the troubleshooter completes its analysis, restart your computer and attempt to download KB5079391 again in Settings.
Method 2: Reset Windows Update services and clear update cache
Illustration: the Windows Update page in Windows 11 Settings
- Press Windows Key + S, type cmd into the search bar, right-click Command Prompt, and choose Run as administrator.
- Stop the primary Windows Update services by typing the following four commands into the Command Prompt, pressing Enter after each:
net stop wuauservnet stop cryptSvcnet stop bitsnet stop msiserver - Press Windows Key + R to open the Run box, type
C:\Windows\SoftwareDistribution, and press Enter. - Highlight all files and folders located inside the SoftwareDistribution directory and delete them.
- Re-open Command Prompt as administrator and restart the core background services by typing:
net start wuauservnet start cryptSvcnet start bitsnet start msiserver
When to use: Use this method if KB5079391 is stuck downloading at a specific percentage or continuously fails because of corrupted installation files stored in the local download cache. Clearing this folder forces Windows 11 to re-download a fresh update package.
Method 3: Repair system files using DISM and SFC tools
- Click the Start menu, search for Command Prompt, right-click the top result, and select Run as administrator.
- Type the following command to repair the Windows component store and press Enter:
DISM.exe /Online /Cleanup-image /Restorehealth. - Wait for the DISM tool to complete its scan and repair operations. This process can take 10 to 15 minutes to complete.
- Once DISM reports successful completion, type
sfc /scannowand press Enter. - Allow System File Checker to scan protected system files and repair any detected corruption.
- Close Command Prompt and restart Windows 11.
When to use: Execute these repair commands if Windows Update fails due to underlying system file corruption or corrupted servicing stores. Once your system completes the restart, navigate back to Windows Update to install KB5079391.
Method 4: Pause and resume Windows Update
- Press Windows Key + I to launch Settings.
- Click Windows Update from the menu options on the left.
- Locate Pause updates on the main panel, click the drop-down menu alongside it, and choose Pause for 1 week.
- Wait approximately 10 to 15 seconds for Windows Update to reset its active thread states.
- Click the Resume updates button located near the top of the Windows Update window.
When to use: This simple toggle clears temporary background connection locks between your device and Microsoft servers without altering system folders. Expect Windows Update to perform a clean scan for KB5079391 immediately upon resuming.
If nothing worked
If KB5079391 refuses to install or continues to fail during the restart phase despite completing these troubleshooting procedures, keep in mind that this is an optional preview release for OS Builds 26100.8116 and 26200.8116 on Windows 11 versions 24H2 and 25H2. Optional updates are designed for testing non-security enhancements prior to broader distribution.
Because KB5079391 contains no security fixes, you do not need to worry about leaving your PC vulnerable. All fixes included in this preview package will be rolled into the mandatory monthly cumulative update released on the next Patch Tuesday. You can safely ignore KB5079391 or pause optional updates in Settings. If you require the specific non-security fixes included in OS Build 26100.8116 or OS Build 26200.8116 immediately, you can perform an in-place upgrade using Windows 11 installation media to repair system files while retaining your personal files and applications.
Sources
Frequently asked questions
Is KB5079391 a required update for Windows 11?
No, KB5079391 is an optional non-security preview update. You can choose whether to install it or wait for its fixes to arrive in the next mandatory monthly security update.
Which OS builds are updated by KB5079391?
KB5079391 applies to Windows 11 version 24H2 and version 25H2, advancing systems to OS Build 26100.8116 or OS Build 26200.8116 respectively.
Is it safe to skip KB5079391 if it gets stuck?
Yes, skipping KB5079391 is completely safe because it contains non-security fixes. All quality improvements will be included automatically in future required updates.
Checked against Microsoft's release notes on ; re-checked when a new build ships.
Covers Windows 11 update releases and the problems that follow them. Tracks Microsoft's release-health notes daily and flags known issues the same day they appear.
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