I am trying to add a language (Tigrinya) that is not listed, but each time I try to save I get this error: "Please, enter required data."
How can I find out "Default locale" or other info of the language that I want to add?
URL of (my) website where problem appears: hidden link
I've just did some research and it seems that language code is "ti" and "Default locale" for Tigrinya language can be: ti_, ti_ER (for Eritrea) and ti_ET (for Ethiopia).
I was able to add this language without any problem on my local installation. Please check screenshot.