Windows 10 Build 15035 is a unique, leaked development build that holds significant value for enthusiasts of ARMv7-based devices like the Microsoft Surface RT and Surface 2
. This specific build, a part of the "Creators Update" cycle (version 1703), is the only known client version of Windows 10 that natively supports the ARM32 architecture. Because it was never officially released, the community developed a specialized Windows 10 Build 15035 Media Builder to facilitate its installation on legacy hardware. What is the Media Builder? Windows 10 Build 15035 Media Builder
is a community-created tool, notably attributed to developer
. It automates the complex process of "kitbashing" official Windows RT recovery files with the leaked Build 15035 Enterprise WIM file to create a bootable installation drive. Key Features and Customization
Unlike official Microsoft tools, this media builder allows for extensive modification of the installation image to suit the limited hardware of Surface RT tablets. Common options during the build process include: Debloating : Options to remove Cortana, Windows Defender, and BitLocker to save resources. Office 2013 RT Integration : A dedicated Office 2013 RT Media Builder
can be used to re-integrate productivity tools, though compatibility is generally limited to English, French, and German. Target Selection
: The script prompts the user to select their specific target hardware (e.g., Surface RT vs. Surface 2) to ensure the correct drivers are included. General Installation Workflow Using the tool generally follows these steps: Windows 10 | Open Surface RT - GitBook
3. Sources of installation files for Build 15035
- Official channels: Insider Preview downloads through the Windows Insider Program — typically via Windows Update, the Insider Downloads page, or ESD/ISO images published to Insider channels.
- Payload formats:
- ESD (Electronic Software Download): Highly compressed install files often provided for Insider and some update distributions.
- ISO: Bootable optical-image format containing the Windows setup and boot files.
- WIM (Windows Imaging Format): Image file (install.wim or install.esd) with one or more Windows editions captured for deployment.
- For build 15035, users commonly encountered ESDs for upgrade and occasional ISOs created either by Microsoft or by community members extracting from ESDs.
The Last Stand of Windows Phone
Build 15035 is widely regarded as the last truly stable, internally usable build of Windows 10 Mobile before Microsoft pulled the plug on active feature development. After this build, the mobile branch entered a "maintenance mode" state (Build 15254).
- OS Version: 10.0.15035.0 (rs2_release_mobdev)
- Architecture: ARM (specifically designed for Qualcomm Snapdragon chips like the 820/821)
- Status: Unreleased to the general public via standard OTA channels.
Legality
Windows 10 Build 15035 is unreleased, leaked software. Distributing the Media Builder tool (which contains no Microsoft code) is legal. However, downloading the actual 15035 system payload is a violation of Microsoft's copyright. You should only do this if you are a registered Windows Insider (though Microsoft no longer provides this build) or for academic/archival purposes.
Part 7: Alternatives to Build 15035
If the Media Builder seems too risky or complex, consider these alternatives:
- Windows 10 Mobile Build 15254: The final, supported (via hacks) build. More stable, better app support.
- Windows 11 on Lumia 950: Through the "Project Renegade" project, you can run full Windows 11 ARM on these phones.
- Sailfish OS: A Linux-based mobile OS that runs on Lumia hardware.
7. Testing and validation
- Virtual validation: First boot and install in VMs, verify driver load, feature set, and Windows Update behavior.
- Application compatibility: Test critical apps against Build 15035 to identify regressions.
- Imaging validation: Check that checksums, digital signatures (if present), and install indexes match expected values.