I solved it by d/l ing the definitions manually & installing them.
In both instances after doing this, my updates started working again.
In the Win X Menu, click on Command Prompt (Admin) to open an elevated Command Prompt.
Type cd /d “\Program Files\Windows Defender” into the Command Prompt and press the Enter key.
If the issue is with your computer or a laptop/notebook you should try using the Reimage Plus Software which can scan the repositories and replace corrupt and missing files.
Once the updates are downloaded, they will be installed – successfully, this time.
To address the issue you may try these troubleshooting steps : 1] Switch from Microsoft Update to using Windows Update.
As far as Windows 8, Windows 7 or Windows Vista goes, you can do this by clicking open Control Panel Uncheck Automatic Updates, Uncheck Recommended Updates and Uncheck use Microsoft Update Service.
Windows Defender is a free program that helps protect your computer against pop-ups, slow performance, and security threats caused by spyware and other unwanted software.
To overcome this problem, today in this topic we are going to share official download links for latest virus definition updates for Windows Defender program.
These links will allow you to download latest virus definition files which can be stored locally on your computer system or on a USB drive.
We are aware of the issue and trying to roll out a mitigation as soon as possible. If you cannot and if you are facing this issue, it is recommended that you update Windows Defender manually periodically till the problem is fixed by Microsoft.
Meanwhile, to get your machine back to a protected state, you can manually download and apply the latest Definition Update. If you don’t want to get into the mess of checking up for updates, downloading them and applying them, I suggest that you use a third-party freeware antivirus software till Microsoft fixes the issue.