Localhost:3000 Application inactive

[Bozon78]

Hello Everybody.
I have a question : when i tape localhost:3000, i just see an icon FB... When i tape on it, it is indicate : application inactive. This application is inaccessible and the developpeur is informed of the problem. Do you have the same issue ? i see in NPM 14/77 users... I think it is correctly running but i don't understand why when i write locahost:3000 it make that...
Other question : i am not sure of the Facebook App ID... Thank you very much