All your Windows Defender is broken thanks to a recent Microsoft Windows Update. The signature update was to fix a file causing system file checks to fail but the patch caused an even bigger issue, making Defender antivirus scans to fail altogether.
The issue was in place for about a day before Microsoft re-patched the antivirus endpoint protection software but not before a ton of press reports and user complaints have gone to the masses.
The fix for that bug was issued on Tuesday in a silent update – but that update ended up causing manual or scheduled Defender malware scans to fail if the “Quick” or “Full” scan options were selected – causing users to take to online forums to report the bug. Real-time scanning was still enabled; and the “Custom” scan option, where users can choose the folders they want to be checked, was also still working, according to reports.
If your in need of Antivirus software Webroot seems to do a pretty good job and it is decently priced.