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Anytime I got to update my system or install a new theme into unity-tweak tool the error message: "cannot find repositories" appears. I have heard about solutions through making changes in the .list files, and solutions saying to create a new etc file. I do not know how to go about these procedures. Can anyone help?

marked as duplicate by karel, Eric Carvalho, Pilot6, user364819, Ravexina Jun 8 '17 at 8:43

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  • It wasn't clear how the OP installed the unity-tweak tool. Fixing his problem could be as simple as clicking a radio button in one of the software & updates tabs. In my answer I sought to provide an answer that included all likely failure modes. – jones0610 Jun 6 '17 at 1:58

There is a very good explanation on how to work with repositories via the desktop GUI at https://help.ubuntu.com/community/Repositories/Ubuntu

This would be the preferred method for newer Ubuntu users.

If you'd prefer to manually edit the files containing repositories, everything you'd ever want to know can be found at http://manpages.ubuntu.com/manpages/zesty/man5/sources.list.5.html

As a starting point and to directly answer your question, /etc/apt/sources.list is the file that contains your repos. There is also stuff in /etc/apt/sources.list.d

Usually, error messages will specify specific repositories that cannot be found by apt update. In that case, you'd edit out that repo from sources.list

The repositories for unity-tweak tool can be found at https://launchpad.net/~freyja-dev/+archive/ubuntu/unity-tweak-tool-daily

If you installed unity-tweak from source or as a Ubuntu package, you'd upgrade it by doing a download from https://launchpad.net/ubuntu/xenial/+source/unity-tweak-tool

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