I am working on an application that integrates with Instagram API to access the user information. I successfully fetch the Access Token using the authorize url but unable to
I got same error. It seems that instagram's spam system disable user's access to any non-official application. Just change user's password. In my case it was help. Also try create another application.
UPD
From my answer to another question
It looks like users get more than one code, and you see first code, but need second. Try relogin users, if you gets error. User will not see instagram page with confirm button, just redirections.
Possible algorithm of error:
1. User click auth link.
2. Get first code.
3. User click auth link (twice, redirection problem, public auth system, etc.)
4. Get another code (even on the same client_id, redirect_uri).
5. You get first code.
6. But first code already doesn't exists.