Microsoft Defender Glitches on Windows 11 After the Latest Update

· 2 min read
Microsoft Defender Glitches on Windows 11 After the Latest Update

Windows 11 has hit a roadblock with its latest cumulative update, causing troubles for some users. People are having issues installing the update, and it's also causing problems with Microsoft Defender, the built-in security program.

Windows Latest has collected complaints about the cumulative update known as KB5029263. This update is necessary for August. A bunch of users are facing problems installing KB5029263. What's more annoying is that even if the update fails, it keeps showing up with a red dot (meaning an update is pending) on the taskbar.

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Some folks are also experiencing more severe issues. For example, the update gets stuck while installing, and File Explorer stops working, so you can't open folders on the desktop.

Interestingly, KB5029263 is also causing trouble for Microsoft Defender, the security app that comes with Windows 11. Some users are seeing an error message when they try to open the app, saying, "Unable to log into Microsoft Defender."

Windows 11 KB5029263 cumulative update / BleepingComputer

According to Windows Latest, this problem might be due to conflicts between the security fixes in the August update and a separate update for Microsoft Defender.

Even though Microsoft hasn't officially acknowledged these problems, including the Defender issues, Windows Latest claims to have talked to a support engineer at Microsoft who confirmed the problem, and the engineer assured me that a fix would be released soon, either as an update for Defender or through Windows Update. So, a solution is on its way.

Microsoft Defender app fails to launch / Image Courtesy -

Problems with installing updates are familiar. Sadly, it's becoming common that some Windows 11 computers fail to install updates successfully. This might affect a small group of users, but it's frustrating because you miss out on important security fixes.

The KB5029263 update also addresses a significant problem for those affected. It fixes a bug that was causing major slowdowns for certain SSDs (solid-state drives). If you have a fast SSD, this bug could have cut its performance in half. If you can't install the August update to fix this issue, it's definitely annoying.