How to Restore Default Repositories in Ubuntu

If you’ve accidentally removed or significantly modified your Ubuntu software repositories, you might need to restore them to their default state. This guide will walk you through the process.

Why Restore Default Repositories?

Restoring the default repositories ensures you have access to stable and tested software packages directly from Ubuntu. This is crucial for:

• Receiving security updates.
• Installing and updating software.
• Maintaining the stability of your system.

Methods to Restore Default Repositories:

1. Using the `software-properties-gtk` Tool (GUI):

   This is a user-friendly graphical method.

   1. Open the “Software & Updates” application (search for it in the Activities overview).
   2. Go to the “Other Software” tab.
   3. Click the “Restore Defaults” button.
   4. Enter your password when prompted.
   5. Click “Reload” to refresh the package list.

2. Using the Command Line (Terminal):

   This method is more direct and suitable for headless servers or users comfortable with the terminal.

   1. Open a terminal window (Ctrl+Alt+T).
   2. Back up your current sources list (optional but recommended):

      sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup

   3. Use the following commands to restore the default repositories. Replace `YOUR_UBUNTU_CODENAME` with your Ubuntu version’s codename (e.g., `jammy` for Ubuntu 22.04). You can find your codename by running `lsb_release -c` in the terminal.

      sudo rm /etc/apt/sources.list
      sudo apt update
      lsb_release -c
      sudo tee /etc/apt/sources.list <<EOF
      deb http://archive.ubuntu.com/ubuntu/ YOUR_UBUNTU_CODENAME main restricted universe multiverse
      deb-security http://security.ubuntu.com/ubuntu/ YOUR_UBUNTU_CODENAME-security main restricted universe multiverse
      deb http://archive.ubuntu.com/ubuntu/ YOUR_UBUNTU_CODENAME-updates main restricted universe multiverse
      deb http://archive.ubuntu.com/ubuntu/ YOUR_UBUNTU_CODENAME-backports main restricted universe multiverse
      EOF
      sudo apt update
      

      **Important:** Replace `YOUR_UBUNTU_CODENAME` with the correct codename for your Ubuntu release in the commands above.

   4. (Alternative command) For systems that have `add-apt-repository` installed, this command will directly recreate the default repositories:

      sudo add-apt-repository --remove 'deb http://archive.ubuntu.com/ubuntu/ [^ ]+ main restricted universe multiverse'
      sudo add-apt-repository --remove 'deb-security http://security.ubuntu.com/ubuntu/ [^ ]+-security main restricted universe multiverse'
      sudo add-apt-repository --remove 'deb http://archive.ubuntu.com/ubuntu/ [^ ]+-updates main restricted universe multiverse'
      sudo add-apt-repository --remove 'deb http://archive.ubuntu.com/ubuntu/ [^ ]+-backports main restricted universe multiverse'
      
      sudo add-apt-repository main
      sudo add-apt-repository universe
      sudo add-apt-repository restricted
      sudo add-apt-repository multiverse
      
      sudo apt update
      

   5. Update the package list:

      sudo apt update

After Restoring:

After restoring the default repositories, it is highly recommended to:

• Run

  sudo apt update

  to refresh the package list.

• Run

  sudo apt upgrade

  to update any outdated packages.

Troubleshooting:

• “Failed to fetch” errors: This usually indicates a problem with your internet connection or a temporary issue with the repository mirror. Try again later or switch to a different mirror in the “Software & Updates” settings.
• “Duplicate source list entry” errors: This means a repository is listed more than once in your sources.list file. Manually edit `/etc/apt/sources.list` or use the `software-properties-gtk` tool to remove the duplicates.