invalid_grant for oauth2/token in Postman and Android app

[chinmayghag08]

I am trying to use the Fitbit Web API in Android app. These are the steps I have followed till now. 

Call 

Step 1 : 

https://www.fitbit.com/oauth2/authorize?response_type=code&
client_id=<client_id>&redirect_uri=<redirect_uri>&scope=<scopes>&expires_in=<milliseconds>

 Get the code on the redirect uri. 

Step 2 :

Calling ""https://api.fitbit.com/oauth2/token" in order to get the access_token in order to get the access to the other web api. 

but when I try to call the above api I get "invalid_grant" with this response code

{
"errors": [
{
"errorType": "invalid_grant",
"message": "Authorization code invalid: <code here> Visit https://dev.fitbit.com/docs/oauth2 for more information on the Fitbit Web API authorization process."
}
],
"success": false
}

This is the same response I get on Postman as well. 

On Postman this is what I did. 

1. Method type :

POST

2. URL Called : 

https://api.fitbit.com/oauth2/token

3. Headers : 

Authorization: Basic <Base64 encoded string of your application's client id and secret concatenated with a colon>

Content-Type: application/x-www-form-urlencoded

4. Body in x-www-form-urlencoded format

clientId : <client id>

grant_type : authorization_code

redirect_uri : <redirect url mentioned in the app>

code : <code that we get from step 1 on the redirect url>

Am I missing on anything? Can someone point in the correct direction? 

[Gordon-C · Accepted solution]

Hi @chinmayghag08 

Based on the information you provided, it should work.   For the authorization code, all you pulling all data between the = sign and the # sign?   For example

https://example.com/?code=29ba1892e2431b1ead152e93c8d4b28c90f5e576#_=_

If you are, would you please try the authorization flow through the OAuth 2.0 Tutorial?   This link will help you get started with it.