You usually update your Windows and its components time to time while connected with internet. Windows 10 operating system is also the newest version or you can say that the newest update of Windows OS. In this version, you get Windows defender program. This feature is used to scan the computer to find out the errors and corruptions. But sometimes when you launch this feature in the computer, you get Windows defender error 87 and there will not any scanning process in the PC until you fix the error. Experts have not found out the exact reasons for the occurring of defender error code 87, but there are some causes responsible for it. They are virus infections, incorrect or corrupt registry files or system files corruption. You should fix Windows error code 87 using the methods provided here in the article. You can fix the issue automatically by downloading and installing Advanced System Repair Tool in the computer.