How To Install & add FlatPak Repository on Ubuntu and Linux Mint system

Flatpak is a software utility for software deployment and package management for Linux. It is advertised as offering a sandbox environment in which users can run application software in isolation from the rest of the system.

Changes in 1.4.3 ( Latest Version ) :

• Fix crash in revokefs.
• Handle 'versions' extension key (in addition to 'version') when
• checking for local extensions, which was causing us to uninstall
• some actually used extensions with uninstall --unused.
• The 'required-flatpak' metadata key now supports listing multiple
• versions to support backported features.
• Fix crash with older versions of polkit.
• Fix installation of bundles.
• Fix crash on deploy error.
• Support building bundles of apps installed from a remote.
• OCI: Fix handling of locally cached icons.
• Fix crash when listing unconfigured remotes.
• Ignore differences in trailing slashes for repo uris.

Install Flatpak on Ubuntu system :

To install Flatpak on Ubuntu 18.10 (Cosmic Cuttlefish) or Ubuntu 19.04 (Disco Dingo), follow this command and run:

sudo apt install flatpak

   
With older Ubuntu versions, the official Flatpak PPA is the recommended way to install Flatpak. To install it, run the following in a terminal:

sudo add-apt-repository ppa:alexlarsson/flatpak
sudo apt update
sudo apt install flatpak

Install the Software Flatpak plugin

The Flatpak plugin for the Software app makes it possible to install apps without needing the command line. To install, run:

sudo apt install gnome-software-plugin-flatpak

How to add repository application from flathub, i installing Wireshark from flathub PPA :

Open flathub link and search what you want to install and open with Software install

After finished you will get nofify open with software centre, like this :

and install this program with click install button