Windows Defender is not updating the latest definition

[T.Y.K]

Windows Defender is not updating the latest definition in my newly installed windows 8. It seems as if something is stopping it form updating the latest definition but I am not sure about the same. Is there anything I can try out rather than uninstalling and reinstalling Windows Defender??

[Viceman]

I want to know if this issue has started suddenly. Do you have any other antivirus installed?? If yes, then uninstall it and cross check if Windows Defender starts updating the latest definition. If not, then you can try installing it manually. You can follow below article for installing the updates manually.
How to manually download the latest definition updates for Windows Defender
If you have any query with the steps mentioned above then you can feel free to ask.

[Allanoo]

I think some of your system files might have got corrected. You can try installing the updates manually but before that I will suggest you to run System File Checker. It will check if there is any missing or incorrect version of protected system files. It will also check if any file has violated integrity. You can refer to below steps for running System File Checker:
Press Windows + X keys, right click on “Command prompt” and run it as admin
Once you get elevated command prompt opened, type “sfc /scannow” without quotes and hit enter.
A scanning process will get started and will let you know if any violation of corrupt file was found. This may take a while to finish, so make sure that you are not interrupting the scanning process in between.

[T.Y.K]

I tried following the article and installing the latest definition updates manually but it gave me an error saying “Cannot find specific path”. I have tried running the “sfc /scannow” command it said “Some core of Windows System Files was broken and has been repaired.” But I don’t think it has made any difference. What should I try out further? Will I have to uninstall and install it again??? If I try to install updates via Microsoft update then it says “Preparing to install” but it doesn’t.

[Manik]

There is some serious issue with Windows Defender in your case. I don’t know what might be the cause of this issue but I can’t think of anything that might help rather than uninstalling and reinstalling Windows Defender. So go ahead with that and post back if that helps.

[Viceman]

Even I will suggest you to uninstall and reinstall Windows Defender. However, rather than uninstalling it form control panel, I will suggest you to use “Windows Defender Uninstaller Tool”. Simply uninstalling Windows Defender from control panel might uninstall it but there are chances that it might leave some instances of Windows Defender in your system which might cause issue while reinstalling it. So using Windows Defender Uninstaller Tool will be a better idea to avoid further issues.