Can't install software from Ubuntu Software

There are many possible reasons why Ubuntu Software (a.k.a. gnome-software) is not working for you. I was having issues with it myself.

1. Firstly, since you started but were not able to complete installs, you probably have an install queue that you need to clear.

   • Make sure Ubuntu Software (gnome-software) is not running. Before making any changes, you want to backup the gnome-software folder that lives in your home directory, which holds the install queue. In Terminal or a CLI:

     cp -r ~/.local/share/gnome-software ~/.local/share/gnome-software-BAK
     

   • Clear the install queue

     rm ~/.local/share/gnome-software/install-queue
     

   • Reopen Ubuntu Software (either from launcher or by typing gnome-software into the command line)

   • If the above doesn't work, you could also try removing your home folder's gnome-software directory altogether. Quit Ubuntu Software, then enter:

     rm -r ~/.local/share/gnome-software
     

   • Restart Ubuntu Software. If that did not help, You can always undo the removal of the gnome-software folder and restore the backup:

     rm -r ~/.local/share/gnome-software && mv ~/.local/share/gnome-software-BAK ~/.local/share/gnome-software
     

2. You could also be having problems because you need to run an upgrade.

   • In Terminal, enter:

     sudo apt-get update && sudo apt-get upgrade`
     

   • Then restart your computer.

3. Your sources list might be causing issues for you. My problems with Ubuntu Software were resolved by fully removing PPA's that I thought I had gotten rid of using add-apt-repository --remove, which did not get rid of their .list files in /etc/apt/sources.list.d/, nor did it get rid of their keyrings in /etc/apt/trusted.gpg.d/. If the software you're trying to install is from a PPA, you could still try cleaning out other PPA's, as these may be slowing down Ubuntu Software. There are known issues with the PPA associated with google-chrome-stable, for example.

   • Edit the list (/etc/apt/sources.list) itself. It's much speedier to do it completely from command line: sudo nano /etc/apt/sources.list then sudo apt-get update. You can also do this in the Software and Updates GUI (run from launcher or open in command line with software-properties-gtk), but it seems to take so much longer to do the updating step when I use the GUI. I can add steps for doing it this way if you want, though.

   • If you already know the names of the PPA's you want to remove then you can get rid of them one by one using the command: sudo add-apt-repository --remove ppa:<repo>/<subdirectory>. Note: There's also ppa-purge, which I didn't want to use because it downgrades packages associated with the PPA to versions available in repositories, and I wasn't sure if this would affect the programs I had installed, as the programs themselves were not the problem.

   • After editing sources.list, you may find (like I did) that old PPA's are still showing up in /etc/apt/sources.list.d (a directory containing .list files of each PPA), and their keyrings were still in /etc/apt/trusted.gpg.d.

     You can check this yourself by entering the command:

     ls -lR /etc/apt/ | grep -v '~'
     

   • Then you can get a list of the .list files in sources.list.d and remove them one by one:

     ls /etc/apt/sources.list.d
     sudo rm -i /etc/apt/sources.list.d/<PPAName>.list
     sudo apt-get update
     

   • To remove the keys:

     sudo apt-key list
     sudo apt-key del <KEY_ID>
     sudo apt-get update
     

After this, Ubuntu Software was actually functioning, hope this helps you!

There's also the possibility you need to do a "deeper" version of sudo apt-get upgrade:

sudo apt-get dist-upgrade

and restart.