How to Restore Default Repositories in Ubuntu

Ubuntu has four standard repositories where software packages are stored: Main, Universe, Restricted, and Multiverse.

  • Main: Free and Open Source Software supported by Canonical.
  • Universe: Community maintained Free and Open Source Software.
  • Restricted: Software that is not totally free.
  • Multiverse: Non-free software.

Out of these four, ‘Main’ is enabled by default, and ‘Restricted’ can be enabled by the user during installation. ‘Universe’ and ‘Multiverse’ can be enabled from the ‘Softwares and Updates’ tool, or by directly modifying the source file (‘/etc/apt/sources.list’) for apt.

If your source file has been broken or corrupted, no apt command can run, and you will not be able to install or upgrade any software.

Let’s see how to restore default repositories in such a case.

Restoring Default Ubuntu Repositories

First, go to the directory where the source file is located.

$ cd /etc/apt
View Ubuntu Source File
View Ubuntu Source File

Now, backup the broken source file. For this, simply rename the file in the same directory.

$ sudo mv sources.list sources.list.bkp
Backup Ubuntu Source File
Backup Ubuntu Source File

Now create an empty source file with the original name.

$ sudo touch sources.list

Now, click on the left top corner of your desktop, search for ‘Software and Updates‘ and open it.

Search Software and Updates
Search Software and Updates

Enable ‘Main‘ by clicking on the checkboxes in front of the respective items. You can also similarly enable ‘Restricted‘, ‘Universe‘ and ‘Multiverse‘, should you wish to do so. Enter a password when prompted.

Enable Ubuntu Repositories
Enable Ubuntu Repositories

Close the window. Click on ‘Reload‘ when prompted, to fetch the package list from the repositories.

Install Software Updates
Install Software Updates

Go back to the terminal. Open the ‘sources.list‘ file again and verify if ‘Main‘ and ‘Restricted‘ repositories have been added.

$ vim /etc/apt/sources.list
Verify Ubuntu Repositories
Verify Ubuntu Repositories

Finally, verify if ‘apt update‘ runs properly.

$ sudo apt update
Verify Ubuntu System Update
Verify Ubuntu System Update
Conclusion

In this article, we saw how to restore the source file for apt, i.e., the list of repositories, back to default.

It is always a good idea to keep a backup of the original source file, before changing anything manually in it. This way, if anything stops working after the change, you can always restore the backup file and run a quick ‘apt update’ to get the apt working again.

If you have any questions or feedback, let us know in the comments below!

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