How to install Windows 11 26H2 without USB using ISO

• You can install Windows 11 26H2 by mounting the ISO directly in File Explorer.
• The method lets you perform an in-place upgrade without creating a bootable USB drive.
• You can also choose “Nothing” under “Change what to keep” to remove your files, apps, and settings.
• Windows 11 26H2 is currently a preview, with Microsoft expected to release the final version in September or October 2026.

You can mount the Windows 11 26H2 ISO directly in File Explorer and run the Windows Setup to upgrade your computer without creating a bootable USB drive. I find this method particularly useful when you want more control over the installation process without reaching for a flash drive or the Media Creation Tool.

This approach works on devices already running Windows 11 as well as on Windows 10. You can use the ISO for an in-place upgrade while keeping your files, settings, and apps, or for a clean installation when you want to start fresh.

A USB flash drive is still the better option when you need to boot into Windows Setup, troubleshoot a computer that won’t start, or perform a clean installation on a new or problematic computer. However, if the operating system is already working normally, mounting the ISO is often the simpler route. You don’t need to create installation media just to launch Setup.

Related

How to clean install Windows 11 26H2

How to upgrade to Windows 11 26H2 (early)

I also recommend choosing the installation method based on the version currently installed on your device. If you’re running an older release of Windows, the ISO provides a straightforward way to move to Windows 11 26H2. If your hardware is already running a version that can transition to 26H2 through an enablement package, however, Windows Update may be the easier and faster option.

I’ve used different installation methods over the years, and the ISO approach remains one of my favorites when I want a clean, predictable upgrade without the extra step of preparing a USB drive.

In this guide, I’ll show you how to install Windows 11 26H2 using an ISO file, including how to perform an in-place upgrade and how to use the ISO for a clean installation without relying on a bootable USB drive or the Media Creation Tool.

Install Windows 11 26H2 by mounting ISO in File Explorer

To install Windows 11 26H2 without a USB flash drive, follow these steps:

1. Download the Windows 11 26H2 ISO file.

2. Open File Explorer.

3. Open the folder location where the ISO file is stored.

4. Right-click the Windows ISO file and select the Mount option.

   Quick tip: If the option isn’t available, select “Open With” and choose the “Windows Explorer” option.

5. Select the mount drive from the left navigation pane.

6. Double-click the Setup file to begin the Windows 11 26H2 upgrade process.

7. Click the Accept button (if applicable).

8. (Optional) Click the “Change how Windows Setup downloads updates” option.

   

9. Select the “Not right now” option.

   

10. Click the Next button.

11. Click the Accept button to agree to the terms.

12. Click the Install button.

    

    Quick tip: Alternatively, you can click the “Change what to keep” option, select the “Nothing” option instead, click the “Next” button, and then click the “Install” button to perform a clean installation.

Once you complete the steps, Windows 11 26H2 will be installed on your computer. In an in-place upgrade, the wizard will skip the initial setup, as it’ll transfer all your settings, apps, and files automatically to the new installation.