How to download Windows 11 26H2 ISO file (preview)

Windows 11 26H2 ISO files can be created early using UUP Dump and Microsoft’s preview build files.
The process downloads build 26300-series releases and converts them into a bootable ISO image.
Rufus can turn the ISO into a bootable USB drive for clean installations or in-place upgrades.
Advanced options allow bypassing TPM, Secure Boot, RAM, and Microsoft account requirements on unsupported hardware.
You can download the latest preview of the operating system from the Microsoft servers or using the UUP Dump tool.

Windows 11 26H2 (2026 Update) is expected to begin rolling out later in 2026, likely around September or October, but you can download the ISO file early in the development process through the Windows Insider Program download page and using the UUP Dump tool.

This approach is ideal for performing a clean installation or an in-place upgrade on a spare computer or virtual machine with the most up-to-date build of the operating system.

The first option is to use the Windows Insider Program page to download the ISO file for the latest preview of version 26H2. One thing to note is that the preview build is still showing as version 25H2, but Microsoft has already flipped the version number to 26H2 in the operating system since preview build 26300.8697.

UUP Dump is a widely used utility that lets you create a custom Windows 11 ISO from publicly available preview builds. It works by downloading the required files directly from Microsoft’s update servers and packaging them into an installation image. While the resulting ISO is unofficial, the files themselves come from Microsoft, making it a reliable option for advanced users and enthusiasts.

In this guide, I will show you how to download the Windows 11 ISO (version 26H2) and create a bootable USB drive using Rufus.

Download Windows 11 26H2 ISO file from Microsoft
Download Windows 11 26H2 ISO file from UUP Dump
Create Windows 11 26H2 bootable USB using Rufus
Pureinfotech’s Take

Important: It’s recommended to create a backup of your computer before installing this version. You have been warned.

Download Windows 11 26H2 ISO file from Microsoft

To download the Windows 11 26H2 ISO file from Microsoft, follow these steps:

Open the Windows Insider page.
Sign in using your Microsoft account credentials (if applicable).
Select the “Experimental (Build 26300.xxxx) – 25H2” option under the “Select edition” menu.

Quick note: Although the option shows up as version 25H2, builds in the 26300 series belong to version 26H2, as Microsoft originally announced. Also, note that the build number will be different depending on when you download the image.
Click the Confirm button.
Choose the product language.
Click the Confirm button.
Click the “64-bit Download” button.

After you complete the steps, you’ll download the Windows 11 26H2 ISO file, the latest preview available from Microsoft’s servers.

Download Windows 11 26H2 ISO file from UUP Dump

To download the Windows 11 26H2 ISO file with the UUP Dump tool, follow these steps:

Open the UUP Dump on the 26H2 page to download the latest build for 26300.xxxx build series.
Select the “Windows 11, version 26H2” option to download the latest (x64) ISO file, for example, build 26300.8597 or any newer release.

Quick tip: If you have a Copilot+ PC or a device using an ARM processor, then download the “arm64” architecture. Also, the build number may be different, depending on when you’re reading this guide. As a result, pick the build with the higher number.
Select the language for the installation in the “Language” setting.
Click the Next button.
Select the version 26H2 editions to include in the Windows 11 ISO file.
Click the Next button.
Select the “Download and convert to ISO” option.
Check the “Include updates (Windows converter only)” option.

Quick note: This step enables the script to integrate the updates, resulting in an ISO file version 26H2.
Click the “Create download package” button to save the tool on your computer.
Open the zip folder with File Explorer.
Click the Extract all button.
Select the location where you want to extract the files.
Click the Extract button.
Right-click the “uup_download_windows.cmd” batch file and select Run as administrator.
Click the More info option.
Click the “Run anyway” button to begin the lengthy process.
Press the “R” key to run the script once, and then press Enter.
Press the 0 key when prompted to close the screen.

Once you complete the steps, the Windows 11 26H2 ISO file will be created inside the folder where you extracted the UUP Dump tool. This process can take up to an hour, depending on your internet connection and how long the script takes to run.

If you encountered an issue while running the UUP Dump script, right-click “Remove_Failure_MountDr_TempDir.cmd” in the script folder and select “Run as administrator”. After the process completes, run UUP Dump again.

Also, ensure your computer has sufficient space for the script to process the files to avoid issues and delays. Usually, the device requires approximately 70GB of free space on the primary drive.

Create a Windows 11 bootable USB using Rufus

To create a bootable USB with Rufus to install Windows 11 26H2, use these steps:

Open the Rufus website.
Click the link to download the latest version under the “Download” section.
Double-click the rufus.x.xx.exe file to launch the tool.
Select the USB flash drive from the drop-down menu under the “Device” section to create Windows 11 bootable media.
Click the Select button.
Select the Windows 11 26H2 ISO file.
Click the Open button.
Select the “Standard Windows 11 Installation” option under the “Image option” setting.
Select the GPT option under the “Partition scheme” section.
Choose the UEFI (non-CSM) option under the “Target system” section.
Specify a descriptive name for the bootable USB drive in the “Volume label” section—for example, “Windows 11 26H2 Setup”.
Use the default settings for the File system and Cluster size options.
Check the Quick format option.
Check the “Create extended label and icon files” option.
Click the Start button.
Clear all the checked options if the computer is compatible with Windows 11.

Quick note: Check the “Remove requirement for 4GB+ RAM, Secure Boot and TPM 2.0” and “Remove requirement for an online Microsoft account” options to create a USB media for unsupported hardware.
Click the Start button.
Click the OK button to confirm the deletion of the USB drive and the creation of the bootable drive.

After you complete the steps, the tool will create a bootable USB drive containing the Windows 11 26H2 installation files.

Alternatively, you can use tools like Ventoy, which allow you to create a bootable USB flash drive by copying multiple ISO files to it. You can even create a bootable media with the Command Prompt.

Pureinfotech’s Take

I still prefer using UUP Dump when I want the latest Windows 11 preview build because it usually gives me access to new releases sooner than Microsoft’s official ISO downloads. Since the files come directly from Microsoft’s servers, I’ve found the process to be reliable over the years, even if creating the ISO takes a little more time.

That said, I wouldn’t recommend installing an early 26H2 build on your primary computer. Preview builds are meant for testing, and even seemingly minor changes can introduce bugs that affect stability or compatibility. A spare computer or virtual machine is a much safer place to explore what’s coming next.

I’ve also noticed that the company has become more comfortable making major changes throughout the development cycle, so the experience you install today may look different by the time 26H2 is officially released. That’s another reason to treat these ISOs as a way to test upcoming features rather than as a version you’ll use every day.

Are you planning to test Windows 11 26H2 before its official release, or will you wait for the final version? Let me know in the comments.

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