Windows 11 26H2 Won’t Install? 10 Proven Fixes That Actually Work (2026)

Microsoft has started rolling out the Windows 11 26H2 feature update to eligible PCs. If your computer is already running Windows 11, you should receive the update automatically through Windows Update. The latest release includes new features, security improvements, bug fixes, and performance enhancements designed to keep your PC secure and up to date.

Unfortunately, the update doesn’t install successfully on every computer. Some users report that Windows 11 26H2 gets stuck downloading, freezes during installation, fails with error codes like 0x800f0922 or 0x80070002, or keeps displaying “Undoing changes made to your computer” after restarting.

In most cases, the issue is caused by corrupted Windows Update files, insufficient disk space, incompatible drivers, third-party antivirus software, or damaged system files, not the update itself. In this guide, we’ll explain why Windows 11 26H2 won’t install and show you 10 practical fixes to troubleshoot the problem and complete the upgrade.

Why Does Windows 11 26H2 Fail to Install?

There isn’t a single reason why the Windows 11 26H2 feature update fails to install. In most cases, the problem is related to your PC’s configuration, corrupted update files, or software conflicts rather than a bug in the update itself.

Some of the most common causes include:

• Not enough free storage space to download and install the update.
• Corrupted Windows Update cache or damaged update components.
• Missing or corrupted system files.
• Outdated or incompatible device drivers, especially graphics and chipset drivers.
• Third-party antivirus or security software interfering with the installation.
• Pending Windows updates or a restart waiting to be completed.
• External USB devices are causing hardware conflicts during the upgrade.
• BIOS or firmware settings that need updating on some devices.

However, most of these problems can be resolved without reinstalling Windows. Follow the solutions below in order, and after each fix, check for updates again by going to Settings > Windows Update and trying to install Windows 11 version 26H2.

1. Restart Your PC and Check for Pending Updates

Sometimes, the Windows 11 26H2 feature update fails because another update is still installing or your PC simply needs a restart. Restarting your computer clears temporary files, completes any pending update tasks, and refreshes Windows services that are required for the installation.

After restarting your PC:

1. Open Settings (Windows + I).
2. Select Windows Update from the left pane.
3. Click Check for updates.
4. Install any available security, cumulative, or driver updates first.
5. Restart your PC again if prompted, then try installing Windows 11 version 26H2.

If the update still won’t install, continue with the next solution.

2. Make Sure You Have Enough Free Disk Space

Windows feature updates require additional free space to download and extract installation files, create temporary files, and complete the upgrade process. If your system drive is running low on storage, the Windows 11 26H2 update may fail to download or stop during installation.

Microsoft recommends having at least 20–25 GB of free space on your Windows drive before installing a feature update.

To free up storage:

1. Open Settings > System > Storage.
2. Review what’s using the most space on your PC.
3. Delete temporary files, Windows Update cleanup files, and items in the Recycle Bin.
4. Uninstall apps or games you no longer use.
5. Move large files such as videos, photos, or downloads to another drive or an external storage device.

After freeing up disk space, restart your computer, open Settings > Windows Update, and click Check for updates to try installing Windows 11 version 26H2 again.

Tip: If your system drive is almost full, avoid installing the update until you’ve cleared enough space. Running out of storage during a feature update can cause the installation to fail or roll back to the previous version.

3. Disconnect Unnecessary External Devices

External devices connected to your computer can sometimes interfere with Windows feature updates. USB drives, external hard disks, printers, webcams, docking stations, and other peripherals may cause driver conflicts during the installation, preventing Windows 11 26H2 from installing successfully.

Before trying the update again, disconnect everything except your keyboard, mouse, and monitor (if you’re using a desktop PC).

This includes:

• USB flash drives
• External hard drives or SSDs
• Printers and scanners
• USB webcams
• Game controllers
• SD card readers
• Docking stations and other USB accessories

Once you’ve disconnected the unnecessary devices:

1. Restart your computer.
2. Open Settings > Windows Update.
3. Click Check for updates.
4. Try installing Windows 11 version 26H2 again.

If the update installs successfully, reconnect your devices one at a time after Windows has finished upgrading.

Note: If you’re using a laptop, keep the power adapter connected during the feature update to avoid interruptions caused by a low battery.

4. Run the Windows Update Troubleshooter

Windows 11 includes a built-in Windows Update troubleshooter that can automatically detect and fix common issues that prevent updates from installing. It checks Windows Update services, verifies system settings, and attempts to repair issues with update components.

To run the Windows Update troubleshooter:

1. Press Windows + I to open Settings.
2. Go to System > Troubleshoot > Other troubleshooters.
3. Find Windows Update and click Run.
4. Wait while Windows scans for update-related problems.
5. If the troubleshooter recommends any fixes, apply them and restart your computer.

After your PC restarts, open Settings > Windows Update and click Check for updates to see if Windows 11 version 26H2 installs successfully.

Note: The Windows Update troubleshooter doesn’t fix every installation problem, but it can resolve common issues such as misconfigured update services, corrupted settings, or minor problems with Windows Update components. If the update still fails, continue with the next solution.

5. Reset Windows Update Components

If Windows 11 version 26H2 still won’t install, the Windows Update cache may be corrupted. Windows stores downloaded update files in the SoftwareDistribution and Catroot2 folders. If these files become damaged or incomplete, the same installation error may appear every time you try to install the update.

Resetting the Windows Update components clears the old cache, restarts the required services, and forces Windows to download a fresh copy of the update.

Reset Windows Update components manually

1. Open Command Prompt as an administrator.
2. Stop the Windows Update services by running these commands one at a time:

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

3. Rename the update cache 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. Restart your computer.

After Windows starts, open Settings > Windows Update, click Check for updates, and try installing Windows 11 version 26H2 again.

Tip: Renaming the SoftwareDistribution and Catroot2 folders doesn’t delete your personal files. Windows automatically recreates these folders the next time it checks for updates.

6. Repair Corrupted System Files Using SFC and DISM

Corrupted or missing Windows system files can prevent feature updates from installing correctly. If essential files used by Windows Update are damaged, the installation may fail, get stuck at a certain percentage, or roll back after restarting.

Windows includes two built-in repair tools that can help:

• System File Checker (SFC) scans for corrupted system files and automatically replaces them with healthy copies.
• Deployment Image Servicing and Management (DISM) repairs the Windows system image that SFC relies on to restore damaged files.

Step 1: Run the DISM command

1. Open Command Prompt as an administrator.
2. Run the following command:

DISM /Online /Cleanup-Image /RestoreHealth

Wait for the scan to reach 100%. Depending on your PC and internet connection, this may take several minutes.

Step 2: Run the SFC scan

After DISM finishes successfully, run:

sfc /scannow

The System File Checker will scan your Windows installation and automatically repair any integrity violations it finds.

Once both scans are complete, restart your computer, then try installing the Windows 11 26H2 update again from Settings > Windows Update.

Tip: If you’re unfamiliar with these tools, check out our detailed guides on how to use DISM to repair Windows and how to run SFC /scannow to understand what each command does and how to interpret the scan results.

7. Temporarily Disable Third-Party Antivirus and VPN

Some third-party antivirus programs, firewalls, and VPN applications can interfere with Windows Update by blocking downloads, interrupting the installation process, or preventing Windows from communicating with Microsoft’s update servers.

If you’re using a security suite such as Bitdefender, Avast, Norton, McAfee, or any other third-party antivirus, temporarily disable its real-time protection before installing the Windows 11 26H2 update. Likewise, disconnect any active VPN connection.

To do this:

1. Disconnect from your VPN (if you’re using one).
2. Right-click your antivirus icon in the system tray.
3. Select an option such as Disable Protection, Pause Protection, or Turn Off Real-Time Protection.
4. Open Settings > Windows Update.
5. Click Check for updates and try installing Windows 11 version 26H2 again.

Once the update is installed successfully, remember to re-enable your antivirus protection and reconnect your VPN if needed.

Important: Only disable your antivirus temporarily while installing the update. Avoid browsing unknown websites or downloading files until you’ve turned your security software back on.

8. Perform a Clean Boot

If Windows 11 version 26H2 still won’t install, a third-party application or background service may be interfering with the update process. Performing a clean boot starts Windows with only essential Microsoft services and drivers, making it easier to identify software conflicts.

A clean boot doesn’t uninstall any programs or delete your files. It temporarily prevents non-essential services and startup apps from loading.

To perform a clean boot:

• Press Windows + R, type msconfig, and press Enter.
• In the System Configuration window, open the Services tab.
• Check Hide all Microsoft services, then click Disable all.

• Switch to the Startup tab and click Open Task Manager.
• Disable all enabled startup applications.
• Close Task Manager, click Apply, then OK.

• Restart your computer.

After Windows starts, go to Settings > Windows Update and try installing the Windows 11 version 26H2 feature update again.

If the update installs successfully, one of the disabled startup programs or third-party services was likely causing the problem. You can re-enable them gradually until you identify the conflicting application.

Tip: Once you’ve finished troubleshooting, open msconfig again and restore Windows to a normal startup so all your services and startup applications load as usual.

9. Install Windows 11 26H2 Using the Installation Assistant

If the Windows 11 26H2 update still fails through Windows Update, try upgrading your PC using the official Windows 11 Installation Assistant. This tool downloads the latest version of Windows directly from Microsoft and performs an in-place upgrade, bypassing many issues caused by a corrupted Windows Update cache or failed downloads.

Before you begin, make sure:

• Your PC is connected to a stable internet connection.
• You have at least 20–25 GB of free disk space.
• Important files are backed up, although the upgrade normally keeps your files, apps, and settings intact.

To upgrade using the Installation Assistant:

• Visit the official Windows 11 Download page on Microsoft’s website.
• Under Windows 11 Installation Assistant, click Download Now.
• Right-click the downloaded file and select Run as administrator.
• Accept the license terms and follow the on-screen instructions.
• Wait while the tool downloads Windows 11 version 26H2 and prepares the installation.
• When prompted, restart your computer to complete the upgrade.

The installation process may take some time, and your PC will restart several times. Keep your computer plugged into a power source and avoid turning it off until the installation is complete.

Tip: The Installation Assistant is often successful even when Windows Update repeatedly fails, making it one of the easiest ways to install the latest Windows 11 feature update without performing a clean installation.

10. Install Windows 11 26H2 Using the ISO File

If the Windows 11 Installation Assistant also fails, you can upgrade your PC using the official Windows 11 ISO. This method performs an in-place upgrade, replacing the Windows system files while keeping your personal files, installed apps, and most settings intact.

An ISO upgrade is particularly useful if Windows Update or the Installation Assistant repeatedly fails due to corrupted update components or installation errors.

To upgrade using the Windows 11 ISO:

1. Download the latest Windows 11 ISO from Microsoft’s official download page.
2. Once the download is complete, right-click the ISO file and select Mount.
3. Open the newly created virtual DVD drive in File Explorer.
4. Double-click Setup.exe.
5. Follow the on-screen instructions.
6. When prompted, choose Keep personal files and apps.
7. Click Install and wait for the upgrade to complete.

Your computer will restart several times during the installation. Depending on your hardware, the process may take anywhere from 30 minutes to over an hour.

Tip: Before starting the upgrade, disconnect unnecessary USB devices, ensure your laptop is plugged into a power source, and temporarily disable third-party antivirus software to reduce the chance of installation errors.

Conclusion

In most cases, the problem is caused by corrupted update files, insufficient storage, outdated drivers, or software conflicts—not the update itself.

Start with the basic solutions, such as restarting your PC, freeing up disk space, disconnecting external devices, and running the Windows Update troubleshooter. If the update still fails, reset the Windows Update components, repair corrupted system files using DISM and SFC, and finally use the Windows 11 Installation Assistant or an ISO file to complete the upgrade manually.

If you’re still seeing an installation error, note the exact error code displayed by Windows Update. That code can help identify the underlying cause and point you to a more specific solution.

Frequently Asked Questions