api answer "error": "unsupported_grant_type"

[1xo2]

thank you so much for posting that code.

the android stops when posting the api the access token from Facebook at
var authenticateResponse = await client.PostAsync (new Uri ("http://localhost:46695/Token"), content);//http://windows:8080/Token
in OnElementChanged
(the Facebook Valid OAuth redirect URIs is : http://localhost:46695/login_success.html )

i have tried to use postman with the facebook accesstoken..
'POST:
http://localhost:46695/Token

HEADERS:
accesstoken: sdbvhjsd.....
grant_type: facebook
'
response by
'{
"error": "unsupported_grant_type"
}'

now: the debugger reached the ValidateClientAuthentication but never got the GrantCustomExtension -- so didnt pass the validation.

yes on both the client (android) and the api where running on 2 instances on visual studio 2017 simultaneously.

i will be happy to get you response.