Microsoft has officially acknowledged a disruptive bug in its latest Windows updates, confirming that the November 2025 non-security preview update KB5070311 (OS builds 26200.7309 and 26100.7309) and subsequent patches are causing RemoteApp connection failures in Azure Virtual Desktop (AVD) environments.
The issue primarily affects enterprise users running Windows 11 versions 24H2 and 25H2, as well as Windows Server 2025, but does not affect all desktop sessions.
Affected organizations report that RemoteApp streams designed to publish individual applications via AVD fail to connect after the update.
This stems from changes to Remote Desktop Protocol (RDP) shell handling, triggered by installing KB5070311 on December 1, 2025. Home and Pro users on personal devices face minimal risk, as AVD deployment is rare outside enterprise settings.
“Individuals using Windows Home or Pro editions… are very unlikely to experience this issue,” Microsoft stated in its support advisory. Enterprise IT teams, however, are scrambling, as disruptions are affecting virtualized workloads that rely on RemoteApp for secure app delivery.
Microsoft urges immediate workarounds.
Option 1 involves manual registry edits: Launch an elevated Command Prompt and run
reg add “HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinLogonShellProgramsRdpShell.exe” /v “ShouldStartRailRPC” /t REG_DWORD /d 1 /f,
then restart. Users must back up the registry first to avoid broader instability.
Option 2 leverages Known Issue Rollback (KIR), Microsoft’s automated mitigation tool. For Pro and Enterprise devices that update directly from Microsoft, the fix rolls out automatically, though it may take up to 24 hours from December 12, 2025, 6:00 PM PT.
A device restart accelerates deployment. Enterprise admins managing updates via IT policies can deploy a targeted Group Policy using the MSI package KB5072033_25121301401. Configure under Computer Configuration > Administrative Templates, then restart affected systems.
Impacted organizations can check the Azure Portal under Messages ID: Q_P4-HFG for tailored insights. Microsoft promises a permanent fix in an upcoming update, after which workarounds can be removed.
This incident underscores ongoing challenges with Windows update reliability in hybrid cloud environments. As enterprises lean on AVD for zero-trust app access, such breaks could expose operational risks amid rising RDP-targeted attacks. IT pros should monitor the Microsoft KB5070311 page and the AVD RemoteApp docs.
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