Microsoft has confirmed a new Windows 11 issue tied to the March 2026 cumulative update KB5079473, and it can be a frustrating one: after installing the update, some PCs may suddenly fail to sign in to Microsoft accounts across multiple popular apps.
According to Microsoft’s update documentation for Windows 11 versions 24H2 and 25H2, KB5079473 shipped on March 10, 2026, and corresponds to OS Builds 26100.8037 and 26200.8037. After wider reporting surfaced in the days that followed, Microsoft added the problem to its known issues list, acknowledging that the update can interfere with Microsoft account sign-ins.
Which apps are affected by the KB5079473 sign-in bug?
Microsoft says the problem can block sign-ins that rely on a Microsoft account inside several everyday apps and services. Reports and Microsoft’s own notes indicate the issue may impact:
Microsoft Teams Free
OneDrive
Microsoft Edge
Word
Excel
Microsoft 365 Copilot
In plain terms, if one of these apps prompts you to log in with a Microsoft account after KB5079473 is installed, you may hit an error loop instead of getting access.
The most confusing part: it may claim you’re offline when you’re not
One reason this bug is catching users off guard is the message it can display. Even when the PC is online, affected devices may show an error implying there’s no internet connection. The message can read along the lines of: “You’ll need the Internet for this. It doesn’t look like you’re connected to the Internet.”
Microsoft believes this is caused by a specific “network connectivity state” that can be triggered after installing the update, leading Windows or apps to incorrectly treat the system as if it can’t reach sign-in services.
Who is (and isn’t) affected
Microsoft’s notes indicate this is limited to Microsoft account sign-in scenarios. Environments that authenticate apps using Entra ID are not affected by this specific issue, which should be good news for many organizations and managed workplace setups.
Microsoft’s current workaround: restart while connected to the internet
Until a permanent fix is released, Microsoft recommends a simple but specific workaround: restart the device while it is actively connected to the internet. Microsoft says this can correct the faulty connectivity state and stop the sign-in failures from returning.
There’s also an important warning: restarting without an internet connection may put the device right back into the same problematic state, potentially bringing the sign-in issue back.
Why this matters for Windows 11 users
KB5079473 is part of Microsoft’s March Patch Tuesday rollout for supported Windows 11 versions, a time when many PCs receive security and quality updates automatically. Because cumulative updates are widely deployed, even a problem that affects “some” devices can still hit a large number of users—especially when it impacts essentials like OneDrive syncing, Edge sign-ins, Teams access, or Microsoft 365 apps such as Word and Excel.
If you’ve installed KB5079473 and suddenly can’t sign in, the best immediate step is to confirm you’re online and perform a restart while connected. If the issue persists, you may need to wait for Microsoft’s follow-up fix as it continues investigating the root cause.
