Here’s what the new Windows Defender bug could do to your PC

Vlad Turiceanu
by Vlad Turiceanu
Editor-in-Chief
Passionate about technology, Windows, and everything that has a power button, he spent most of his time developing new skills and learning more about the tech world. Coming from a solid background in PC... Read more
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  • Choosing an antivirus to keep your PC protected should be the main concern for everyone nowadays.
  • Users that trust Windows Defender to scan their PCs for malware now face a new threat.
  • The most recent bug to hit this software creates such a file backup that it freezes the UI.
  • Fixing the issue is not that hard, as it requires a new update to be applied.
Windows Defender bug

Users are now dealing with a problem which puts so much pressure on they’re PCs that it could even lead to the operating system having a slow response time.

The bad news is that the actual issue we are talking about is caused by one of Windows’ built-in security features.

Windows Defender bug fills up Hard Disk Drive

Even though Microsoft Defender wasn’t the public’s number one choice when it came to protection software, in recent years it started to slowly make a comeback into users’ preferences.

According to user reports on Reddit, this new bug affects PC performance by creating hundreds of thousands of duplicate files, taking up most of the disk space available.

To be more specific, when the real-time protection feature is turned on, in a short time span, the Windows Defender scan folder will fill up with thousands of files no larger than 1kb or 2kb.

To make you understand the scale of this system clog, a folder that usually takes up almost 1Gb, is now as big as 30Gb. This can, in some cases, cause the UI or even the entire system to freeze.

This cluster of files appear under:

C:\ProgramData\Microsoft\Windows Defender\Scans\History\Store

How can I fix this?

In order to restore your system to its former glory and get rid of all these unwanted and, let’s face it, useless files, all you have to do is update Windows Defender.

From the Settings menu, visit the Windows Update options and simply check if there is an update for Defender. Once the software has finished patching to version 1.1.18100.6, this issue will be taken care of.

However, you are now left with the tens of gigabytes of surplus files. To delete them simply go to the location we mentioned above, enable the view of hidden items, and delete all of them.


There are alternatives to using Windows Defender as the main antivirus software on your PCs. However, if you still trust it and want to continue using it, you can do so knowing that this issue has been fixed.

Tell us if this article was helpful towards solving this issue for you in the comments section below.

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