API Literacy · Level 2
Reading the response
Mission briefing
Mission 2-B: A contact form keeps failing. Users fill it out, hit submit, and get a vague red error. No one can reproduce it reliably. The answer is sitting in the response — you just have to learn to read it.
Every response comes with a status code — a three-digit number that says how it went. 200 means success. 400-something means you sent something wrong. 500-something means the server broke. The form's coming back 401. That's not random — that's a specific story.
Open the response body. It's JSON — that format with the curly braces and key/value pairs. It's just structured text, organized so both humans and machines can read it. The JSON here says { "error": "missing token" }. That's the actual reason.
A 401 with 'missing token' means authentication failed. The form tried to submit without proving who it was. Authentication is the login check — the 'are you allowed to do this' step. The form's knock on the door had no ID attached.
I look closer. The proof of identity is supposed to ride along in the request headers — the little envelope of info attached to every request. This one's envelope is empty. Now I can describe the bug precisely instead of saying 'it's broken.'
You found the form returns a 401 with "missing token." How do you write up the bug?