Microsoft released KB5079473 on 10 March 2026 for Windows 11 versions 24H2 and 25H2 as part of its regular Patch Tuesday updates. As with any monthly cumulative update, it included important security fixes along with a handful of quality improvements.
When the update first rolled out, it quickly attracted attention online. Reports started appearing of crashes, freezes, broken apps, sign-in problems, and even boot issues. A few weeks later, the picture is much clearer. Some of the concerns were real, one key issue has now been fixed by Microsoft, and at least one widely reported problem turned out not to be caused by the Windows update at all.
Here’s what happened, what’s been confirmed, and what users should do now.
What KB5079473 actually affected
The main issue Microsoft has officially confirmed after installing KB5079473 involved Microsoft account sign-ins.
Some users found that apps relying on a Microsoft account suddenly stopped signing in properly and displayed a false message claiming the PC was not connected to the internet. This affected apps and services such as Microsoft Teams Free, OneDrive, Microsoft Edge, Word, Excel, and Microsoft 365 Copilot when a Microsoft account login was required.
Importantly, this problem affected consumer Microsoft accounts, not organisations using Microsoft Entra ID.
So while early reports described a broad range of failures, the sign-in bug is the main issue Microsoft formally acknowledged as a known problem linked to KB5079473.
Microsoft has already issued a fix
Microsoft responded by releasing KB5085516 on 21 March 2026 as an out-of-band update.
This update specifically fixes the Microsoft account sign-in bug introduced after KB5079473. If a user was seeing false “no internet” messages when trying to sign in to Microsoft apps, installing KB5085516 should resolve it.
For most users, that means the correct path now is not to remove KB5079473 unless absolutely necessary, but instead to move forward to KB5085516 or later.
If your system is otherwise stable, that is the best option.
The Samsung laptop drive issue was not caused by KB5079473
One of the more alarming stories in March involved certain Samsung Galaxy Book systems appearing to lose access to the C: drive, often with “Access denied” errors that broke apps and prevented normal use of the system.
That issue was real, but Microsoft’s investigation concluded that it was caused by the Samsung Galaxy Connect app, not by KB5079473 itself.
That matters because early reporting often treated this as another example of the March Windows update breaking machines. Microsoft’s current position is that this was a Samsung software issue, not a fault in the cumulative update.
So if a Samsung device has this specific problem, the answer is to follow Samsung- or Microsoft-provided recovery guidance for the Galaxy Connect issue rather than blaming KB5079473 alone.
Secure Boot and boot failures are more complicated than they first appeared
Another concern linked to the March update involved systems failing to boot and showing errors such as “Windows Boot Manager blocked by current security policy.”
Early explanations often suggested that KB5079473 simply replaced old Secure Boot certificates and that older PCs could not cope with the change. The reality is more nuanced.
Microsoft has been preparing Windows devices for the expiration of older 2011 Secure Boot certificates in June 2026, and KB5079473 expanded the set of systems eligible to receive newer certificates. However, this rollout is still being handled in a controlled way rather than as a universal overnight switch.
According to Microsoft’s guidance, some boot failures appear to happen because certain UEFI firmware implementations are faulty. Instead of correctly appending new Secure Boot data, some firmware may overwrite the existing database. If that happens, the system can lose trust entries it still needs and end up blocking the Windows bootloader.
In practical terms, that means these Secure Boot problems are often better understood as a firmware compatibility issue exposed during certificate servicing, rather than a simple case of the Windows update “breaking boot.”
If you are seeing Secure Boot or Windows Boot Manager policy errors after updating, the first thing to check is BIOS/UEFI firmware updates from the device or motherboard manufacturer.
What about the crash reports, freezes, gaming BSODs, and broken apps?
This is where things need a bit more care.
There have absolutely been community reports of crashes, freezes, blue screens, app instability, and other odd behaviour after KB5079473. Some users have reported system instability after startup, failures resuming from sleep, and problems affecting certain apps or hardware combinations.
But as of 30 March 2026, Microsoft has not formally listed broad gaming, graphics, audio, or general BSOD problems as known issues for KB5079473.
That does not mean those reports are false. It does mean they should be treated as unconfirmed or hardware-specific reports, rather than established widespread faults affecting all or most users.
For businesses and IT teams, that distinction matters. There is a difference between:
- an issue Microsoft has confirmed and fixed,
- an issue caused by a third-party app,
- and individual user reports that may depend on very specific drivers, firmware, or software combinations.
A newer March update exists, but it is not the main one to recommend
Microsoft also released KB5079391 on 26 March 2026 as an optional preview update. It includes additional changes and fixes, but it is not the best update to point people toward as the main solution here.
That is because Microsoft temporarily paused parts of its rollout after some devices encountered installation error 0x80073712.
So for anyone affected by the confirmed KB5079473 sign-in problem, KB5085516 remains the more relevant and safer recommendation than jumping straight to the late-March preview update.
What users should do now
If your PC is running normally after KB5079473, there is no strong reason to remove it simply because of the stories circulating online. The better approach is to stay current and install KB5085516 or later.
If you are experiencing the Microsoft account sign-in bug, the most important step is to check Windows Update and install the March 21 out-of-band fix.
If you are on a Samsung laptop and suddenly cannot access the C: drive, look specifically at the Samsung Galaxy Connect issue rather than assuming the cumulative update is solely to blame.
If your PC will not boot and you are seeing Secure Boot errors, focus on firmware updates and Secure Boot troubleshooting before repeatedly uninstalling and reinstalling Windows updates.
If your machine has become unstable in ways that do not match the officially confirmed sign-in issue, it may still be worth testing a rollback of the latest cumulative update as a temporary troubleshooting step. But that should be treated as a last resort, because uninstalling security updates is never ideal for long-term protection.
The bottom line
KB5079473 was not the all-round disaster some early reports made it sound like, but it also was not completely smooth.
One genuine post-update issue did affect Microsoft account sign-ins, and Microsoft has already fixed that with KB5085516. A separate Samsung drive-access problem caused understandable concern, but that turned out to be linked to Samsung software rather than the Windows update itself. Beyond those confirmed issues, there are still scattered reports of crashes and instability, but they have not been formally recognised by Microsoft as widespread KB5079473 faults.
For most users, the sensible advice is straightforward: keep Windows updated, install the latest fix, and only roll back if you are dealing with a serious problem that can clearly be linked to the update.
Last updated: 30 March 2026