Get OAuth token fails to get access token but works from 3rd party client such as PostmanIssue Get OAuth token fails to get access token but works from 3rd party client such as Postman . Common errors seen are "error":"Unauthorized","message":"Full authentication is required to access this resource"error='invalid_request', description='Missing parameters: access_token'"error":"invalid_client","error_description":"Invalid client credentials"ReleaseMadrid and earlierCauseThe OAuth consumer expects the client authentication to be sent as basic auth header. This can be verified by sending the OAuth call from POSTMAN with 'Client Authentication' set to 'Send as Basic Auth header'. This call successfully gets the access token. If the same call is made with 'Client Authentication' set to 'Send client credentials in body' it fails .ResolutionStarting from New York release, in the OAuth application registry record there are 2 different options to 'Send Credentials' : As Basic Authorization headerIn Request Body If a OAuth Provider is expecting authentication in basic authorization header: In New York release you can select the option "As Basic Authorization header" In Madrid and below we could only send authentication 'In Request Body'. The only work around is to make a REST call to get the OAuth token.