Unable to locate package [duplicate]

Solution 1:

First, check if the package actually exists:

1. Go to packages.ubuntu.com with a web browser.

2. Scroll down to "Search package directories"

3. Enter the package which you're trying to install into the "Keyword" field.

   Enable "Only show exact matches:"

   Change the "Distribution" to the codename of the version of Ubuntu you're using, e.g. focal in Ubuntu 20.04 or it's displayed by lsb_release -sc

   

If there are no results, the package you are looking for doesn't exist and the next steps will not work. It may require a third party PPA or an alternative installation method.

If results are found, the package exists and you may continue with these steps:

1. Open Software Sources (or Software & Updates in 13.04+) by searching for it in the Dash.
2. Open the "Ubuntu Software" tab.
3. Ensure that the first 4 checkboxes on this tab are enabled:

4. Update the package lists, then test with these commands:

<pre>
sudo apt update
sudo apt install <i>&lt;TEST_PACKAGE&gt;</i>

Solution 2:

There are many questions about this topic. Here I provide a basic/general answer.

When apt-get install is unable to locate a package, the package you want to install couldn't be found within repositories that you have added (those in in /etc/apt/sources.list and under /etc/apt/sources.list.d/).

The following (general) procedure helps to solve this:

1. Make sure you have enabled Ubuntu repositories:

   To enable all repositories (main, universe, restricted, multiverse), use the following commands:

   sudo add-apt-repository main
   sudo add-apt-repository universe
   sudo add-apt-repository restricted
   sudo add-apt-repository multiverse  
   

   Visit Help for more information.

2. For finding PPA for more packages:

   • Go to Ubuntu Package Search. ^{(Already explained in this answer)}
   • If the package that you are unable to locate is from a PPA go to the PPA and check if it is available there for your release.
   • For External Repositories, Visit Ubuntu Updates and search by button. or Visit PPAs.
   • Or Search in Launchpad ppa
   • Find appropriate ppa according to your Ubuntu release version.

3. Add PPA (by command-line):

   Use this command:

   sudo add-apt-repository ppa:<repository-name>
   

   Visit Ubuntu community help for more information.

4. Don't forget to update (make apt aware of your changes):

   It is essential to run this command after changing any repositories:

   sudo apt-get update
   

   Selecting best download server may help to speed up update.

5. Finally install the package:

   sudo apt-get install <package>
   

   Refer to Package management by commandline.

Additional/Tip: you can find the correct package-name (i.e the name in the repository) using apt-cache search <package-name>.

• Related frequently asked Q&A:

1. How do I resolve unmet dependencies after adding a PPA?
2. What does "Package <package> has no installation candidate" mean?

Note: If package is not available on repository any how, than you have to wait until it is available (in the case of new/updated versions) or use other installation processes than apt-get e.g. compiling from source, downloading executable binary, etc.