Illegal redirect_uri - how to show my own page

[SandraHeinz]

Hello there again 🙂 

I am making my web app where user inserts his personal secret data (User ID, Client ID, Client secret etc), after that he confirms loggin in via Spotify web. 
I want to solve some errors and I cant manage one thing. When user insert wrong data in browser will open window with message "Illegal redirect_uri" and others. And I want to show my own html template (working in Python with Flask). Any ideas please? 

I checked status code, but it returns 200. I tried to get html code via response.text, but I got html from Spotify Login Page instead of basic html with Illegal redirect_uri message. 

Thanks in advance for any tips.

[Ximzend]

Have you added it to the dashboard of your app and clicked save? Maybe you should add a :port number and http:// in front of it.

[SandraHeinz]

@Ximzend hello 👋 yes, my redirect_uri looks like this "http://127.0.0.1:5555/callback". When I enter my correct credentials/ dashboard data it works perfectly, but I want to manage (besides other errors) when other user enters any data wrong (so its not only about illegal redirect uri, abut also for example "INVALID_CLIENT: Invalid client ")