“Missing Grant Type Parameter” in Auth0 Delegation endpoint

I’m trying to call (POST) the Auth0 delegation endpoint with the below request suggested by Auth0, from Postman.
P.S. “client_id” and “id_token” are replaced with respective values.

Content-Type: application/json

{
  "client_id":   "{CLIENT_ID}",
  "grant_type":  "urn:ietf:params:oauth:grant-type:jwt-bearer",
  "id_token":    "{YOUR_ID_TOKEN}",
  "target":      "lwTL1rYVfC0KsBUFPeKWY3HvGjbIgdDM",
  "api_type":    "salesforce_api",
  "scope":       "openid"
}

I’m getting the below error, where as the grant_type parameter is included in the request above.

{
    "error": "invalid_request",
    "error_description": "Missing grant_type parameter"
}

Can someone please suggest where I’m going wrong there.

The issue is with the Content-Type HTTP header; the correct value should be application/json and you’re passing 'application/json' (notice the use of single quotes in the one that is invalid).

The incorrect content type then leads to the error in question because the body could not be understood and the first parameter that the endpoint complains about is the grant_type. You likely copy/pasted this from the Authentication API explorer which is indeed displaying the incorrect value; I already informed the docs team about this issue.

@jmangelo : Thanks for your comment. I did remove the single quotes in the content-type eader while POSTing from POSTMAN. I just copy pasted here the exact lines given in the auth0 post. The issue is occurring when the header in POSTMAN is without single quotes. I’ll try to edit the post above as well if it is misleading. Thanks again for your comments. If you could share more thoughts, it will be of great help.

@jmangelo : I tried with a different browser extension based REST Client and got a different error as below:
{
“error”: “unauthorized_client”,
“error_description”: “Grant type ‘http://auth0.com/oauth/legacy/grant-type/delegation/id_token’ not allowed for the client.”,
“statusCode”: 403,
“error_uri”: “Application Grant Types
}
I also somewhere in this forum came across a post that Delegation is deprecated in Auth0 now. So is that the issue?

I tried with a different browser extension based REST Client and got a different error as below:

{ "error": "unauthorized_client", "error_description": "Grant type 'http://auth0.com/oauth/legacy/grant-type/delegation/id_token' not allowed for the client.", "statusCode": 403, "error_uri": "https://auth0.com/docs/clients/client-grant-types" }

I also somewhere in this forum came across a post that Delegation is deprecated in Auth0 now. So is that the issue?