Problem updating windows defender
First check whether you are using a 32-bit or 64-bit version of Windows 10/8.1/7.
Once you know the version of Windows installed on your device, download the installers from the following links: You can also update Windows Defender definitions using Windows Power Shell.
Here is the tutorial with some effective ways to fix this issue on Windows 8 and update Windows Defender right away.
Windows Defender is the default AV pre-installed in Windows 8.
Windows 8.1, Windows 8 or Windows 7 The Automatically diagnose and fix common problems with Windows Update troubleshooter may automatically fix the problem described in this article.
Tried regular checks to verify system components and online image and windows update service diagnostics, cleaned up Software Distribution, turned off non-Microsoft auto starting services, - all to no avail. The Windows Defender does not update via Windows Update, but, somehow.
So, run malware scan using the elevated command prompt. Hope the steps described above help you fix issues with the update of Windows Defender in Windows 8 and update the Windows Defender successfully so that you can scan your system with the updated definition.