Authorization Endpoint does not support data in the RequestBody as required by Section 4.2.1 Authorization Request of the OAuth 2.0 standard

Question

Section 4.1.1. Authorization Request states:

The client constructs the request URI by adding the following parameters to the query component of the authorization endpoint URI using the application/x-www-form-urlencoded format, per Appendix B:

The use of the Content:Type x-www-form-urlencoded forces the request parameters to be sent in the body and not the query header. However, when submitted this way the authorization server returns an error indicating it cannot locate the client_id.

Is there a setting I need to change to support the request in the body rather than in the header?