Authentication process canceled with Spotify auth (invalid_client)

[khamaileon]

I can't authenticate myself to the Spotify API. I've got an Authentication process canceled exception.

AuthCanceled at /complete/spotify/

When I look at the bottom of the problem:

def handle_http_errors(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except requests.HTTPError as err:
            print(err.response.text)
            if err.response.status_code == 400:
                raise AuthCanceled(args[0])
            elif err.response.status_code == 503:
                raise AuthUnreachableProvider(args[0])
            else:
                raise
    return wrapper

give me:

{"error":"invalid_client"}

with no further details :(