Microsoft’s March Patch Tuesday update for Windows 11 has introduced a bug that makes affected devices believe they have no internet connection, even when they’re clearly online. The result is that a string of core Microsoft apps — Teams Free, OneDrive, Edge, Word, Excel, and Microsoft 365 Copilot — lose the ability to sign in with a Microsoft account, effectively rendering their online features useless.

If your school deployed KB5079473 this month and users are reporting that apps keep telling them they’re offline, the problem is not your network. It’s the update.

What’s actually happening

KB5079473 was released on 10 March 2026 as a cumulative update for Windows 11 24H2 and 25H2 (OS Builds 26100.8037 and 26200.8037). Microsoft has now confirmed on its Windows release health dashboard that the update can put devices into what it describes as “a specific network connectivity state” that breaks Microsoft account authentication.

The error message users see is the particularly unhelpful: “You’ll need the Internet for this. It doesn’t look like you’re connected to the Internet.”

The device is connected. The browser works. Other apps work. But Windows’ internal assessment of its own connectivity has gone wrong, and every Microsoft app that checks that state before attempting a sign-in gives up before it even tries to reach Microsoft’s authentication servers.

This is what makes the bug so time-consuming to diagnose. It sends users and IT staff down entirely the wrong troubleshooting path — checking Wi-Fi, restarting routers, fiddling with DNS — when the actual fault is a broken connectivity flag inside Windows itself.

Which apps are affected

Microsoft’s confirmed list of affected applications:

  • Microsoft Teams Free
  • OneDrive
  • Microsoft Edge
  • Word
  • Excel
  • Microsoft 365 Copilot

Any feature in those apps that requires a Microsoft account to authenticate is potentially broken. That includes OneDrive sync, Edge profile sync, Copilot access, and Teams sign-in.

Who is and isn’t affected

This is a Microsoft account issue only. Organisations using Microsoft Entra ID (formerly Azure Active Directory) for authentication are not affected. The Entra ID sign-in flow takes a different authentication path and doesn’t hit the same connectivity state check.

For schools, this means:

  • Managed devices signed into Microsoft 365 Education via Entra ID — should be fine
  • Personal Microsoft accounts on school devices — at risk
  • Teams Free users (rather than the full Teams client tied to an Entra licence) — at risk
  • Staff personal devices using OneDrive personal sync or consumer Microsoft accounts — at risk
  • Students working from home on personal machines with the update installed — at risk

The problem is that mixed-account environments are common in schools. Even on a well-managed estate, someone will have a personal OneDrive or a consumer Microsoft account signed in somewhere. Those are the sessions that break.

The workaround

Microsoft’s advice is disarmingly simple: restart the device while it’s connected to the internet. This repairs the faulty connectivity state and should prevent the issue from recurring.

It works in most cases, and it’s something you can communicate directly to users without IT needing to touch each machine. The caveat is that some devices may re-enter the faulty state, requiring another restart.

Microsoft has confirmed it’s investigating a permanent fix but hasn’t published a timeline. Given the breadth of affected apps and the visibility of the issue, expect either an out-of-band patch or a fix rolled into next month’s cumulative update.

Whether to roll back or delay the update

KB5079473 is a cumulative security update. Rolling it back or pausing deployment means leaving security patches unapplied, which is a real trade-off.

For schools running a clean Entra ID-managed environment with no consumer account dependencies, the risk from this particular bug is low. Deploy as normal.

For schools with mixed environments — personal accounts, shared devices, Teams Free users — it’s worth testing on a subset of devices before pushing the update estate-wide. If devices are already affected, the restart workaround is low-friction enough to manage while waiting for a proper fix.

A rough month for Patch Tuesday

This isn’t the only problem with March’s update batch. The same Patch Tuesday cycle has been linked to reboot loops, system freezes, and a separate issue affecting C: drive access on certain Samsung laptops. Microsoft has also had to ship out-of-band emergency patches for Bluetooth visibility problems and security flaws in the Routing and Remote Access Service.

Monthly cumulative updates are supposed to be low-drama events. When they break core functionality — particularly something as fundamental as “can your apps see the internet” — it creates exactly the kind of friction that makes IT teams want to delay updates. Which creates its own security risks. It’s a cycle that Microsoft keeps feeding.

What to do now

If you’re seeing these errors across your Windows 11 estate:

  1. Confirm KB5079473 is installed — Settings > Windows Update > Update history, look for the 10 March 2026 update
  2. Check whether affected users are on personal Microsoft accounts or Entra ID — this determines whether the bug applies
  3. Tell affected users to restart while connected to the internet — this is Microsoft’s current workaround
  4. Watch the Windows release health dashboard for a confirmed fix

The fix will come. In the meantime, the restart workaround is reliable enough to keep things moving.