Microsoft’s January 13, 2026 security update (most notably KB5074109 for Windows 10 and Windows 11, along with related server updates) introduced a bug that disrupts Remote Desktop authentication when using the new Windows App.
As a result, users are unable to complete credential prompts when attempting to connect via Remote Desktop.
Who Is Affected
The issue impacts several Microsoft remote access services, including:
- Azure Virtual Desktop (AVD) login flows
- Windows 365 Cloud PC sign-in
- Remote Desktop connections made through the Windows App on client devices
When users click Connect in the Windows App, the session fails almost immediately. In many cases, the credential prompt never completes or returns an instant authentication error, preventing the RDP session from starting at all.
This behavior has been reported across multiple versions of Windows 10 and Windows 11, as well as Windows Server 2019 through Windows Server 2025.
Cause and Microsoft’s Response
According to Microsoft’s official documentation and public statements:
- The problem is a known regression in the January 2026 cumulative update, specifically affecting how the Windows App handles credentials after the update is installed.
- Microsoft has confirmed that a fix is being prepared and will be released as an out-of-band update (outside the normal Patch Tuesday cycle).
- In some update rings, Microsoft has enabled Known Issue Rollback (KIR) to automatically reduce impact, although details on availability remain limited.
Impact Details
Azure Virtual Desktop and Windows 365
- Credential prompts fail to complete inside the Windows App.
- Users typically see errors such as “Unable to authenticate” before the session even begins.
Windows App Sign-In Failures
- The Windows App is unable to properly pass credentials to the underlying RDP engine.
- This issue is unrelated to older Remote Desktop protocol bugs seen in past updates.
Broad OS Coverage
- Multiple Windows client builds are affected.
- Several Windows Server releases are also impacted, particularly in enterprise and VDI environments.
Temporary Workarounds
Until Microsoft releases a permanent fix, the following workarounds have proven effective:
Use the Classic Remote Desktop Client
- The traditional Remote Desktop Client (mstsc.exe) continues to work for many users and is the most reliable short-term solution.
Use the Web Client
- For Azure Virtual Desktop and Windows 365, connecting through the browser-based web client bypasses the Windows App entirely and avoids the issue.
Avoid Uninstalling the Update
- While removing the January security update can restore Remote Desktop functionality, it also removes important security fixes and is generally not recommended unless absolutely necessary.
Microsoft’s Fix Status
Microsoft has publicly acknowledged the Remote Desktop authentication failures and confirmed that remediation is underway. As of January 18, additional fixes have begun rolling out that address some of the broader issues introduced by the January update, including Remote Desktop login problems.
| Category | Details |
|---|---|
| Update Date | January 13, 2026 |
| Primary Update | KB5074109 (Windows 10 / Windows 11) |
| Affected Component | Windows App (new Remote Desktop client) |
| Issue Description | Credential prompt fails or authentication errors occur immediately when initiating Remote Desktop connections |
| User Experience | Clicking Connect results in instant sign-in failure or incomplete credential prompt |
| Affected Services | Azure Virtual Desktop (AVD), Windows 365 Cloud PC, Remote Desktop via Windows App |
| Affected Operating Systems | Windows 10, Windows 11 (multiple builds), Windows Server 2019, 2022, and 2025 |
| Root Cause | Regression in January 2026 cumulative update affecting credential handling in the Windows App |
| Microsoft Status | Issue acknowledged; fix in progress |
| Planned Resolution | Out-of-band update (non–Patch Tuesday) |
| Mitigation from Microsoft | Known Issue Rollback (KIR) enabled for some update rings |
| Recommended Workaround | Use classic Remote Desktop Client (mstsc.exe) |
| Alternative Workaround | Use browser-based web client for AVD / Windows 365 |
| Not Recommended | Uninstalling the January security update (reduces security posture) |
| Fix Rollout Status | Partial fixes began rolling out around January 18, 2026 |
