Windows defender program is a very dynamic and best feature introduced in the Windows OS 10. You can use this program to scan the computer to remove virus and other infections. But sometimes when you launch this program to scan the computer, you get Windows defender error 127 on the computer screen. The issue will harm the computer data and other components very much if not fixed within time. However, there is no any exact reason for the occurring of defender error code 127. But sometimes you get it due to the corruption of the system files associated with this program. You should fix Windows error code 127 using the manual or automatic error fixing methods recommended here in the article. For automatic fixing, you can download and install Advanced System Repair Tool in the computer.