Receiving OAU-250 Unsupported Grant Type Getting OAUTH Token from Code

Also, the documentation states grant_type should be a parameter, we tried it as a Query parameter, we also tried passing JSON in the POST body. Which should it be? I'm running Fiddler and I'm very sure of what I'm passing. Thanks.

Show me the exact post call you made and how you pass the body in a form data (not a json object)

Check this API reference.

Thanks, the documentation page I had called them post parameters, your reference called them form data. When I added them as form data it worked. I think this has tripped me up before with the API documentation.