Microsoft warned customers they might experience up to 30 minutes of black screens when logging into Azure Virtual Desktop (AVD) after installing the KB5040525 Windows 10 July 2024 preview update.

Additional symptoms include single sign-on (SSO) failures (on Office applications such as Outlook and Teams) blocking connections to backend services or preventing data syncs and Office apps losing network connectivity while other apps like Edge retain access to the Internet and the local network.

"This issue is caused by a deadlock in the interactions between the Azure Active Directory(AAD) broker and the underlying AppX deployment service(AppxSvc) and Background tasks infrastructure service," Microsoft explained in a new entry added to the Windows release health page on Friday. 

"Please note that this issue is different from the scenario where the AppX Deployment Service (AppxSvc) was in an invalid state, causing a black screen. That issue was resolved with Windows updates released on October 22, 2024 (KB5045594), and later."

This known issue is more likely to appear when using FSLogix user profile containers, commonly used in virtual environments like remote desktops.

Windows 10 Education edition users and home users of Windows Home or Pro editions are unlikely to experience this black screen issue since Azure Virtual Desktop is more regularly used in enterprise environments.

Azure Virtual Desktop is a cloud-based desktop and app virtualization service that allows customers to use Windows desktops over the Internet via Windows, Mac, iOS, Android, or HTML5-based clients.

Microsoft first unveiled it as 'Windows Virtual Desktop' in September 2018 and made it generally available worldwide one year later, following a public preview testing phase.

In June 2021, the company rebranded the virtual desktop infrastructure platform to Azure Virtual Desktop, adding new security capabilities and pricing options for remote app streaming.