Thoughtful PM
Problem installing using default Software Install

There are many application which cannot be found in the Ubuntu Software Center but available as a download from the respective sites. For example, I wanted to install Google Chrome and Google offers Chrome for Ubuntu or Debian. Clicking on the link automatically triggered the default installer "Software" or "Software Install". From Ubuntu 20.x there has been an issue around opening .deb file or downloaded Ubuntu application.
Resolving the Issue
Open Terminal and run the following command -
sudo apt install gdebi-core
Once installed use Gdebi now as the package installer.
To install the downloaded Google Chrome installer (file name is google-chrome-stable_current_amd64.deb), open the Terminal. Go to Downloads folder and execute the following command to install Chrome -
sudo gdebi google-chrome-stable_current_amd64.deb
Once the application has been installed it should appear in the Applications.



