Keep getting missing client_secret when using Twitch API (OIDC Authorization Code Flow)

API
2

The reason you’re getting a 404 is because you’re POST’ing to the wrong URL. https://api.twitch.tv/kraken/oauth2/token should be https://api.twitch.tv/api/oauth2/token

POST https://api.twitch.tv/api/oauth2/token
    ?client_id=<your client ID>
    &client_secret=<your client secret>
    &code=<authorization code received above>
    &grant_type=authorization_code
    &redirect_uri=<your registered redirect URI>