Not working with new Spotify's URI's security requierments

I am very new to arduinos and coding but I thought this was a cool little project.

Everything went fine until I entered my ESP8266 URL in my web browser, I managed to connect to my Spotify account but then I get the following error message : "INVALID_CLIENT: Insecure redirect URI"

I am using "http://192.168.0.26:8000/callback/" as my REDIRECT_URI, I choose port 8000 randomly that might be the problem?

I, of course, entered the exact same URI in my https://developer.spotify.com/ project.

Any help would be REALLY appreciated! Thank's!!!