The latest round of Windows 10 updates appear to have introduced a bug into Windows Defender, the OS's built-in antivirus software, though it has not been officially acknowledged yet. Regardless, some users are reporting a Windows Defender pop-up message saying that it has skipped a file "due to exclusion or network scanning settings."
This happens during both quick scans and full scans. After being alerted to the issue on Bleeping Computer, I fired up a quick scan on my own PC and was able to consistently reproduce the message. Here's a screenshot I took:
Under normal circumstances, this would not be an error—you can configure Windows 10 to skip over certain files, which can come in handy if you are running software that trips up Windows Defender with a false-positive detection.
I never set any exclusions, and for good measure, I triple checked the settings page where that can be done. It was blank.
Günter Born, who first reported the issue at BornCity, told BleepingComputer that 80 percent of his German readers confirmed the bug on their own PCs. Other reports of this behavior date back to March 10. Likely not by coincidence, that is when Microsoft began pushing out this month's Patch Tuesday update (a collection of security updates issued on the second Tuesday of every month).
It's not yet clear which specific update is confusing Windows Defender, or which specific files the AV software is skipping over. Hopefully Microsoft will push out a fix soon.
I've not seen a need to venture beyond Windows Defender these days, but if you are looking for an alternative (free or paid), check out our roundup of the best antivirus for PC gaming.