Rooting a Googlebook renders the "Cast My Apps" cross-device feature unusable, preventing users from streaming Android app screens to their laptop.
The limitation was first highlighted by Magisk lead developer John Wu (@topjohnwu) on X (via Android Authority). According to Wu, the connection is blocked on the smartphone side because the rooted Googlebook fails Hardware Key Attestation checks.
Smartphone Blocks Connection Due to Failed Hardware Key Attestation
Investigating why Cast My Apps failed on Magisk-rooted Googlebooks, Wu discovered that connected Android smartphones explicitly reject incoming casting requests from devices that fail Hardware Key Attestation validation.
Obtaining root privileges prevents the Googlebook from satisfying hardware-level attestation requirements. As a result, the paired smartphone flags the laptop environment as untrusted and terminates the streaming connection.
On Android devices, root access routinely breaks security-sensitive applications such as Google Wallet, mobile banking apps, and DRM-protected media platforms.
Because Cast My Apps relays screen output and real-time user inputs directly to an external computer, strict hardware verification is enforced to prevent sensitive session data from being exposed to tampered operating system environments.
While Googlebooks have faced separate bugs disabling Cast My Apps during tethering, this specific root limitation is an intentional security safeguard rather than a software defect.
Magisk v31.1 Beta Introduces Googlebook Support
The news comes shortly after Magisk officially rolled out support for Googlebooks in the latest Magisk v31.1 beta build.
Official documentation now outlines the setup process, including patching and flashing recovery GPT images via USB drives and managing pre-granted root permissions adapted for Googlebook OS's multi-user environment (HSUM).
However, potential users should note that acquiring root access completely disables key cross-device functionality like Cast My Apps before deciding to modify their devices.