August 2026 Windows Update — Known Problems and Fixes

August's Windows update has been out for three days. One problem has surfaced. Here's what it is and what you should do.

Fake "Turn on Virus Protection" warning

After installing KB5121003, some Windows 11 PCs are showing a persistent "Turn on Virus Protection" notification in Windows Security. Looks alarming. Your antivirus is fine.

The alert appears about four minutes after you log in, at the same uptime mark every time. Consistent enough that people spotted it wasn't random. Microsoft support has confirmed this is not a real problem: Windows Defender is fully active. The notification is wrong. It's a display bug in Windows Security, not a genuine warning about your protection.

Reports have come in from Windows 11 users on Microsoft Community Hub and the ElevenForum KB5121003 thread. Different manufacturers, different hardware configurations, all seeing the same notification at the same moment after login. That consistency is what told Microsoft this is a bug. No fix has been released yet. They're collecting reports to formally confirm it before a patch goes out.

In the meantime, you have two options.

First: ignore it. Your PC is protected. Defender is running; the display is simply wrong.

Second: check for yourself. If you'd rather see that everything's fine with your own eyes, you can do that in about a minute.

How to confirm your antivirus is working

1. Press the Windows key on your keyboard. It's the key with the four-part flag symbol, usually at the bottom-left next to the space bar.
2. A search bar appears. Type Windows Security and press Enter.
3. The Windows Security app opens. In the left-hand menu, click Virus & threat protection. If there's no visible menu, click the three horizontal lines at the top-left of the app first to open it.
4. Look at the top of the page. You should see a green tick and the words No action needed.

If you see that, Defender is working normally. The notification you got is a bug. Dismiss it and carry on.

Should you still install the update?

Yes. The security fixes in this update patch real threats, including CVE-2026-68820, an actively exploited zero-day that security researchers at Check Point traced to North Korea's Lazarus Group. It also closes 42 Critical vulnerabilities across Windows, Word, and Excel. Don't skip it over a false antivirus notification.

The notification is annoying, but harmless.

If something else has gone wrong since the update, or you're seeing errors you can't explain, that's what local computer repair is here for.

Mark

Mark has been fixing computers since the late '90s and went self-employed in 2008. Based in St Helens since 2013, he works evenings and weekends from his home in Laffak — friendly, affordable repairs for PCs, laptops, and Macs. See reviews on Google