Hello Windows Insiders, today we are releasing Windows 11 Insider Preview Build 25905 to the Canary Channel. We are releasing ISOs for this build – they can be downloaded here.

Starting with today’s build, Windows Insiders in the Canary Channel will notice that the name of the branch shown in the desktop watermark has changed back to RS_PRERELEASE. As a result of this change, Insiders will notice that some features that were previously removed temporarily with the switch over to ZN_RELEASE have now returned – in addition to some new features mentioned below.

REMINDER: As builds released to the Canary Channel are “hot off the presses,” we will offer limited documentation for builds flighted to the Canary Channel including documenting only the most significant and highly impactful known issues. Please note that we will not publish a blog post for every flight – only when new features are available in a build.

What’s new in Build 25905

New features from the Dev Channel

This build includes new features from the Dev Channel, such as Dev Drive, Backup and Restore improvements (Windows Backup), Dynamic Lighting, the Windows App SDK version of File Explorer and Gallery, and more.

Rust in the Windows Kernel

Rust offers advantages in reliability and security over traditional programs written in C/C++.  This preview shipped with an early implementation of critical kernel features in safe Rust. Specifically, win32kbase_rs.sys contains a new implementation of GDI region. While this is a small trial, we will continue to increase the usage of Rust in the kernel. Stay tuned!

[We are beginning to roll this out, so the experience isn’t available to all Insiders in the Canary Channel just yet as we plan to monitor feedback and see how it lands before pushing it out to everyone.]  

Arm32 UWP App deprecation

Starting in this Insider Preview build in the Canary Channel, we have removed support for Arm32 UWP applications from Windows on Arm, as documented here: Windows 11 Specs and System Requirements. After the OS upgrade, any installed Arm32 applications will no longer launch on your device. Note that this does not affect Arm64 applications.

• During setup, you will see a message with a list of applications that are currently Arm32 installed on the system.
• In many cases, the list of impacted applications will be reduced by manually forcing the Microsoft Store to install any pending application updates prior to the OS upgrade. To do this, launch the Microsoft Store application, choose “library”, then click on the “Get Updates” button.
• After the OS upgrade is complete, to fix any Arm32 applications, you will need to manually uninstall then reinstall those applications from the Microsoft Store. By doing so, you will install a compatible version that will run on your device.

New PostAuthenticationAction support for terminating individual processes in Windows LAPS

Thank you everyone who gave us feedback on the new Windows Local Administrator Password Solution feature which we shipped a few months ago. Several customers pointed out that the new Post Authentication Actions feature (PAA) only handled termination of interactive logon sessions. This meant that PAA was not able to terminate specific individual processes that were launched in an OTS (over-the-shoulder) elevation scenario, for examp