WebAPI Authorization Code with PKCE 400 Error

[Aidan3214]

Hello all,

I am working on a small project to request player information from the WebAPI, however I am having a lot of issues with authentication. 

My Question or Issue

I have been following https://developer.spotify.com/documentation/web-api/tutorials/code-pkce-flow PKCE authentication guide as I am doing a single webpage application. 

I have followed the guide and even copied the code directly, I have also tried using the GitHub example authorization_code_pkce. However, no matter what I do I get a bad request: 400 when requesting the access token. 

I cannot see from any of the documentation where the formation error is coming from in the api/token POST request. Can any offer any guidance?

Is the previously provided documentation and guides out of date considering the recent API changes?

Thanks