WSO2 Oauth2 Authentication - Provided Authorization Grant is invalid - oauth

Question

I'm testing the WSO2 Identity server using the Oauth 2.0 with a Python login application. The routine which I adjusted from another IdP server, throws an error at the token authorization step, after successfully passing through step 1 which is obtaining the request code. The error returning from the WSO2 server is:
"Provided Authorization Grant is invalid"
Console Log
*** start of login ***
Code received = 23618215e0ee701b973f548a3f8e7dda
Token Request Answered = <Response [400]>
Token Request Text = {"error":"invalid_grant","error_description":"Provided Authorization Grant is invalid."}
Token Request URL = https://extbasicpacman05.podc.sl.edst.red.com:9443/oauth2/token
Token Request Encoding = None
Code:
#print "Send Token Request now"
# prepare lookup of token using code as input
verify='/home/claudef/tmp/oauth_2/oauth/wso2.pem'
url = "https://extbasicpacman05.podc.sl.edst.red.com:9443/oauth2/token"
payload = { 'client_id': client_id, 'client_secret': client_secret, 'grant_type': 'authorization_code', 'code': str(code), 'redirect_uri': 'http://localhost/resources/oauth2Callback' }
urllib.urlencode(payload)
headers = { 'application' : 'x-www-form-urlencoded' }
r = requests.post(url, data=payload, headers=headers, verify=verify)
print "Token Request Answered = " + str(r)
print "Token Request Text = " + str(r.text)
print "Token Request URL = " + str(r.url)
print "Token Request Encoding = " + str(r.encoding)
Any hint how to fix the authorization grant using a code value is welcome.

Answer 1

Just identified the error cause, indeed its a coding error, as the callback URL contained a missing port definition. I've corrected the statements to the new setting and the token returned successfully from the WSO2 server. The problem is solved.
The error message "invalid grant" is somehow confusing, maybe a suggestion
for future improvements.
verify='/home/claudef/tmp/oauth2/oauth/wso2.pem'
url = "https://extbasicpacman05.podc.sl.edst.red.com:9443/oauth2/token"
payload = { 'client_id': client_id, 'client_secret': client_secret, 'grant_type': 'authorization_code', 'code': str(code), 'redirect_uri': 'http://localhost:8080/resources/oauth2Callback'}
urllib.urlencode(payload)
headers = { 'application' : 'x-www-form-urlencoded' }
r = requests.post(url, data=payload, headers=headers, verify=verify)