Microsoft has released an emergency out-of-band update for Windows 11 after its March 2026 security patch broke Microsoft account sign-in across several major apps. If Teams, Outlook, OneDrive, or Office have stopped working properly on your PC since the last update, this fix is for you. Here is everything you need to know about what went wrong, what the emergency update does, and how to get it on your machine right now.
What Happened — The March 2026 Update That Broke Microsoft Apps
On March 10, 2026, Microsoft released its regular monthly Patch Tuesday update, identified as KB5079473, for Windows 11 versions 24H2 and 25H2. Shortly after installation, users began reporting that several Microsoft apps lost internet connectivity and could no longer sign in using a Microsoft account. The affected apps include Microsoft Teams, Outlook, OneDrive, Office applications, Edge, and Copilot. Enterprise users signing in with enterprise-grade accounts were not affected — the problem was specific to personal Microsoft account authentication on consumer and prosumer devices.
The issue stems from how KB5079473 changed the way Windows 10 or 11 handles Microsoft account connectivity. The update introduced a regression that interrupted the authentication flow for apps relying on personal Microsoft account sign-in, effectively locking users out of Microsoft’s own software suite on their own machines.
The Emergency Fix — KB5085516 Explained
Microsoft’s emergency response is update KB5085516, released on March 21, 2026 as an out-of-band (OOB) patch. Out-of-band means it was pushed outside the normal monthly update schedule specifically because the issue was serious enough to require an immediate fix. The update applies to Windows 11 versions 25H2 and 24H2, upgrading builds to 26200.8039 and 26100.8039 respectively.
KB5085516 restores Microsoft account sign-in functionality across all affected apps. It contains all quality improvements from the original KB5079473 update, meaning you do not lose any of the security fixes from March’s Patch Tuesday — you just get those fixes without the sign-in breaking bug. The patch takes approximately five to seven minutes to apply and requires a restart.
Critically, this update does not download automatically for most users. Forbes and Windows Latest both confirmed that KB5085516 will not appear as an automatic update for everyone and must be manually sought out or downloaded directly from the Microsoft Update Catalog. If your apps are broken right now, waiting for the update to arrive on its own may not resolve the issue quickly.
How to Install KB5085516 on Windows 11
Method 1: Windows Update Settings
Open the Start menu and go to Settings. Select Windows Update and click Check for Updates. If KB5085516 is available for your device it will appear in the list. Click Download and Install. Your PC will restart once the installation is complete. This method works if Microsoft has begun rolling the update out to your specific build — availability is being staged gradually.
Method 2: Microsoft Update Catalog (Fastest Method)
If the update does not appear in Windows Update, download it directly from the Microsoft Update Catalog at catalog.update.microsoft.com. Search for KB5085516 and download the version matching your Windows 11 build — 25H2 or 24H2. Run the downloaded installer, follow the prompts, and restart your PC. This bypasses the staged rollout entirely and gets the fix on your machine immediately regardless of when Microsoft schedules the automatic delivery to your device.
How to Check Your Windows 11 Version Before Downloading
Press Windows Key + R, type winver, and press Enter. The About Windows dialog shows your exact build number. If you see build 26200 you are on 25H2 — download the 25H2 version of KB5085516. If you see build 26100 you are on 24H2 — download the 24H2 version. Installing the wrong build version will not break your PC but the update will fail to apply.
Is Your PC Affected? How to Check
Your PC is likely affected if all of the following are true: you are running Windows 11 version 24H2 or 25H2, you installed the KB5079473 update released on March 10, 2026, and you use a personal Microsoft account rather than an enterprise or work account to sign in to apps. The clearest symptom is that Teams, Outlook, OneDrive, or Office prompts you to sign in but fails to connect after you enter your credentials, or shows a connectivity error even when your internet connection is working normally.
If you are having network issues that predate the March update, those are separate problems unrelated to KB5085516. This emergency patch specifically addresses authentication failures in Microsoft account apps — it does not fix general internet connectivity problems.
What If You Haven’t Installed KB5079473 Yet
If you have not yet installed the March 10 Patch Tuesday update, Microsoft recommends installing KB5085516 directly rather than installing KB5079473 first. The emergency update contains all the security improvements from KB5079473 without the sign-in regression, so you can skip the broken update entirely and go straight to the fixed version. Check your installed update history by going to Settings, Windows Update, and Update History to confirm whether KB5079473 is already on your system.
Should You Roll Back the Update Instead
Rolling back KB5079473 is possible but not recommended as a long-term solution. The March Patch Tuesday update contains important security fixes that protect your system from vulnerabilities. Removing it leaves your PC exposed until you reinstall those patches. Installing KB5085516 is the cleaner approach — you keep all security improvements while eliminating the sign-in bug. If your Windows Update is stuck or refusing to install either update, that is a separate issue worth troubleshooting before proceeding.
Affected Apps — Full List
Microsoft confirmed the following apps lose Microsoft account connectivity after installing KB5079473 without the emergency fix: Microsoft Teams (personal and free versions), Microsoft Outlook, Microsoft OneDrive, Microsoft Office applications including Word, Excel, and PowerPoint, Microsoft Edge when signed in with a personal account, Microsoft Copilot, and any third-party app that uses Microsoft account sign-in through the standard Windows authentication flow. Enterprise users authenticated through Azure Active Directory or Entra ID are not affected — the issue is isolated to the personal Microsoft account authentication pathway.
People Also Ask
What happens if I don’t install the Windows 11 emergency update?
If you already have KB5079473 installed and do not install KB5085516, your Microsoft account apps including Teams, Outlook, OneDrive, and Office will continue to experience sign-in failures and connectivity errors. The underlying security patches from March’s Patch Tuesday remain in place, so your PC is not less secure — but the app functionality disruption will persist until the fix is applied. Microsoft has not indicated a timeline for automatic rollout to all devices, so manual installation is the fastest resolution.
Does the emergency update affect Windows 10?
KB5085516 is specifically for Windows 11 versions 24H2 and 25H2. Windows 10 users were not affected by the sign-in regression introduced in KB5079473, and the emergency out-of-band patch does not apply to Windows 10. Microsoft released a separate extended security update for Windows 10, KB5078885, earlier in March as part of the ongoing extended support program for Windows 10 users who have not upgraded.
Is it worth upgrading to Windows 11 in 2026?
Yes for most users, despite incidents like this month’s patch issue. Windows 11 receives more frequent performance improvements, better hardware support, and longer security update commitments than Windows 10. Microsoft’s extended security support for Windows 10 ends in October 2025 for most users, meaning Windows 10 machines will stop receiving free security patches. Emergency patches like KB5085516 are rare — Microsoft typically resolves them within days — and the overall security posture of Windows 11 remains stronger than continuing on an unsupported Windows 10 installation.
Workarounds While Waiting for the Update
If you need Teams, Outlook, or OneDrive working immediately and cannot install the update right now, several temporary workarounds reduce the disruption. For Outlook and Office, try signing out of your Microsoft account within the app and signing back in — some users report this temporarily restores functionality. For OneDrive, right-click the system tray icon, select Settings, then Account, and attempt to unlink and relink your account. For Teams, using the web version at teams.microsoft.com bypasses the desktop app authentication issue entirely until the fix is installed.
These workarounds are not guaranteed and vary by device configuration. Installing KB5085516 through the Microsoft Update Catalog remains the only confirmed permanent fix. If after installing the update your apps are still misbehaving, restart your PC fully rather than using sleep or hibernate — a cold restart ensures the patch applies cleanly to all system components currently running on your PC.
How to Prevent Similar Issues in the Future
Microsoft’s out-of-band update history shows that major sign-in and connectivity regressions from Patch Tuesday updates happen roughly once or twice per year. The safest practice for home users is to delay automatic update installation by one to three days after Patch Tuesday — enough time for early adopters to surface critical bugs before your machine installs the patch. Go to Settings, Windows Update, Advanced Options, and use the Pause Updates feature to delay installation by a few days each month. Enterprise IT administrators typically test updates in a ring deployment before pushing to all devices for exactly this reason.
Keeping a current system restore point also means you can quickly repair your PC to a working state if a future update causes similar disruption. Search for Create a restore point in Windows, ensure protection is enabled for your system drive, and create a manual restore point before each major update cycle.
Full-stack developer at Scylla Technologies (USA), working remotely from Bangladesh. Adobe Certified Magento Developer.
