Cannot add PPA. Please check that the PPA name or format is correct

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

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 :)

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.