Invalid Client on Access Token Request(401 Invalid client)

I am currently writing an app, but everytime I am redirected back to my callback URL, I am having this error

I think I have done my configs correctly but why I am still gettings this error? Here’s a photo of my client_id and secret(I purposely darken some parts but you can still see that my config are identical).


Can anyone help me here?I am able to get access tokens from Postman but on a live website still no luck.


I have dug deeper into the PHP SDK package and it seems that the GuzzleHttp codes are deprecated. The SDK is using the ‘body’ parameter for the requests and it is deprecated on the newer Guzzle http clients. the body parameter should be changed to ‘form_params’