There’s currently a major bug in Windows Defender, the free antivirus software that ships with Windows 10.
Running a Quick or Full scan will fail after a few seconds and only go through a handful of files, resulting in incomplete, superficial results. Such scans are usually known to take tens of minutes, and even hours.
The issue has been widely reported over the past two days on the Microsoft tech support forums [1, 2, 3, 4, 5], Reddit [1, 2, 3, 4], and tech support sites like AskWoody, DeskModder, BornCity, and Bleeping Computer.
