You'll need a new app to open this windowsdefender10 Sep 2020
Recently I purchased a used ThinkPad T4301 from ebay. However, when I tried to open the Windows Defender, I saw the following pop-up:
Apparently, this happens if you unistall a third-party Anti-virus software. But it is easy to fix it by following steps
Open Powershell with elevated (Admin) access
Run following command
That’s it. Done!