Internet connection is working.

apt-get is working.

Trying to add ppa:cooperjona/lightread but an error has raised:

Cannot add PPA 'ppa:cooperjona/lightread' . Please check that the PPA name or format is correct.

I supposed there is an error in writing or in the PPA.

I tried also the 'ppa:tombeckmann/ppa' but with same error.

  • The issue comes from your system, not the PPA, which works fine for me.
    – MrVaykadji
    Mar 5, 2014 at 12:01
  • I tried all of this here and still got the same error. Jun 19, 2014 at 20:21
  • If anyone of you ends up here and is using a proxy, check this thread instead
    – eis
    Nov 17, 2015 at 11:27
  • @Anwar: I don't understand how the two are related. The accepted answer here is about certificates and not web proxy servers. May 18, 2017 at 22:16
  • @DavidFoerster The linked answer has addressed both the issue and I feel that it's same problem with different answers.
    – Anwar
    May 19, 2017 at 5:03

3 Answers 3


Open Terminal and run the command:

sudo apt-get install --reinstall ca-certificates

It may work, but if doesn't then run:

sudo -E add-apt-repository ppa:ppaname/ppa

Instead of:

sudo add-apt-repository ppa:ppaname/ppa

  • 6
    note to reader: sudo -E preserves the user environment, including any proxy config.
    – eis
    Apr 29, 2016 at 12:04
  • Or if you're on a https restricted network and have to install another root certificate to trust the networks MITM policy, here's something that will help: askubuntu.com/questions/645818/…
    – Tim Lewis
    Dec 14, 2017 at 2:16

I googled the error and find this. So i tried to clone a git as he did there and has the same result.

So to solve this:

sudo apt-get install --reinstall ca-certificates

and things become smooth again :)

  • 7
    I tried this, but the same error exist and it does not work, ain't it odd? Dec 6, 2014 at 5:20

I had this exact error message about checking the PPA name or format. My network was connected and I could ping websites and browse fine.

What I finally figured out was the clock on my computer was set wrong. If it's off more than a small amount, the secure connection will fail and it will report this message. It's very unhelpful.

Check your clock. I set mine and then it immediately worked as expected.

  • 1
    Another issue causing this issue is a firewall (like Shorewall) blocking access to the internet. I had the exact same message - there was no other indication that the firewall was blocking.Though it worked after opening a port.
    – Deckard
    Jun 13, 2018 at 10:54

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