Ubuntu – How to open “apt” links in Firefox (in Lubuntu)

• Neither gDebi, Synaptic or Lubuntu Software Center support handling the "apt://" protocol/links.

• But a very simple graphical apt-get-type installer called AptURL does.

  • Install it with sudo apt-get install apturl
  • Set Firefox Preferences to "Always Ask" for apt
  • Click on a link, and select AptURL:

  

  • And the window will pop open:

  

  • Installation will take place using a lightweight gDebi-style frontend

• The other option is to use a custom script such as green7's answer

• But to be browser-independent, what you really need is:

  1. A .desktop file for your script/application, indicating that it handles the x-scheme-handler/apt protocol (see MimeType= lines in aptURL.desktop, ubuntu-software-center.desktop)
  2. And you can set the default by modifying the defaults.list file in /usr/share/applications/

Hit Ctrl+Alt+T to open terimanal and run following commands:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install firefox

If doesn't solve the problem then try following solutions:

• Reinstall/install the language pack:

  sudo apt-get install --reinstall language-pack-en
  

• (Re-)Generate and reconfigure locales:

  sudo locale-gen
  sudo dpkg-reconfigure locales
  

• The Final solution is to manually set LANG variable by modifying /etc/default/locale.
  Open /etc/default/locale in your favorite editor:

  gksudo gedit /etc/default/locale
  

  and set the LANG= to en_US.UTF-8 or whatever language you're using, like:

  LANG=en_US.UTF-8
  

  Changes will take effect after reboot.

After the additional information provided by OP, problem got solved by running:

sudo apt-get clean
sudo apt-get install firefox

_{Sources: Ubuntu documentation, Ubuntu forums, Super User}