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Microsoft has issued an out-of-band urgent update to fix a severe problem impacting Remote Desktop connections on Windows client devices.
This issue arose immediately after the implementation of the January 2026 security update, labeled as KB5074109. Users and administrators reported extensive credential prompt errors when trying to log in via the Windows App, greatly hindering access to Azure Virtual Desktop and Windows 365 setups.
The initial update, launched on January 13, 2026, aimed to tackle usual security vulnerabilities and flaws for systems operating on certain Windows builds.
However, soon after its rollout, users found that they could no longer authenticate correctly when starting remote sessions, affecting organizations dependent on virtual desktop infrastructure, as staff were unable to reach their cloud-hosted workstations.
Failures in Remote Desktop Connection
The underlying technical issue was pinpointed to a regression in how the Windows App manages credential prompts on specified OS builds (Builds 26200.7623 and 26100.7623).
When users made connection attempts, the authentication interface failed to process credentials accurately, leading to repeated sign-in failures. This inadvertently barred users from accessing remote environments, even after entering valid usernames and passwords.
The repercussions were especially pronounced for enterprise settings utilizing Azure Virtual Desktop and Windows 365, where the Windows App functions as the main access point for connectivity.
The error was confined to the client-side processing of connections, implying that the server infrastructure remained operational, but client devices were incapable of completing the necessary handshake to initiate the session.
Resolution
Microsoft recognized the issue promptly and accelerated a solution. The company has now provided a standalone “out-of-band” update, KB5077744, specifically crafted to rectify the regression caused by the prior update.
This correction reinstates standard functionality to the Windows App and guarantees that credential prompts behave as intended during Remote Desktop sessions.
System administrators overseeing affected endpoints are urged to implement KB5077744 without delay to restore service availability. This update raises the OS build numbers to 26200.7627 and 26100.7627.
Patch Information
| Type of Update | KB Identifier | Date of Release | Affected Builds | Corrections |
|---|---|---|---|---|
| Problematic Update | KB5074109 | Jan 13, 2026 | 26200.7623, 26100.7623 | Security corrections (led to RDP failure) |
| Resolution Update | KB5077744 | Jan 17, 2026 | 26200.7627, 26100.7627 | Corrects credential prompt failure |
Impacted Platforms
| Platform | Component | Symptoms |
|---|---|---|
| Azure Virtual Desktop | Windows App | Credential prompt failure / Sign-in error |
| Windows 365 | Windows App | Credential prompt failure / Sign-in error |
| Windows Client | Remote Desktop | Failure to connect to remote host |
Administrators may obtain the corrective patch directly from the Microsoft Update Catalog or via their traditional update management channels, such as Windows Server Update Services (WSUS) and Microsoft Intune.
Implementing this update does not necessitate the removal of the preceding security patch, ensuring that devices remain safeguarded against the vulnerabilities addressed on January 13 while restoring remote access.
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