Error while generating access_token using Ebay 's REST API - Python requests

I'm trying to use the ebay REST-API for the first. I am simply trying to generate an access_token using the client credentials grant-request. I followed the instructions here https://developer.ebay.com/api-docs/static/oauth-client-credentials-grant.html

HTTP method:   POST
  URL (Sandbox): https://api.sandbox.ebay.com/identity/v1/oauth2/token

  HTTP headers:
    Content-Type = application/x-www-form-urlencoded
    Authorization = Basic <B64-encoded_oauth_credentials>

  Request body (wrapped for readability):
    grant_type=client_credentials&
    redirect_uri=<RuName-value>&
    scope=https://api.ebay.com/oauth/api_scope

I'm getting this error: {'error': 'invalid_client', 'error_description': 'client authentication failed'} and my code looks like this:

path = 'https://api.sandbox.ebay.com/'
app_json = 'application/json'

headers = {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Authorization': base64.b64encode(b'Basic CLIENT_ID:CLIENT_SECRET')

}

payload = 'grant_type=client_credentials&redirect_uri=Searchez&scope=https://api.ebay.com/oauth/api_scope'

def get_oath_token():
    url = 'https://api.sandbox.ebay.com/identity/v1/oauth2/token'
    r = requests.post(url, headers=headers, data=payload)
    print(r.json())

get_oath_token()

What do I have configured incorrectly? Thanks.

Solution

You're base64encoding "Basic " and shouldn't be. The doc says just encode your Client ID + ":" + Client Secret, and leave the word "Basic" and the space that follows it alone.