I need to send an HTML string to the backend to be processed. To do this I am using Angular's HttpClient. However, the framework refuses to give me any meaningful error message other than a 400 response code. Below is my code.
Service method:
exportTestAsPdf(testHtml: string): Observable<any> {
    return this.http.post<any>(this.baseTestApiUrl + "Print", `\"${testHtml}\"`, this.requestHeaders);
}
requestHeaders:
protected get requestHeaders(): { headers: HttpHeaders | { [header: string]: string | string[]; } } {
  const headers = new HttpHeaders({
    Authorization: `Bearer ${this.authService.accessToken}`,
    'Content-Type': "application/json",
    Accept: "application/json, text/plain, */*"
  });
  return { headers };
}
ASP.NET endpoint:
[HttpPost]
public IActionResult Print([FromBody] string testHtml)
{
    // Code here
}
It doesn't give me 404 so I know the endpoint is found. What is the problem?
I followed the answers in this SO post but those did not help me.
 
     
    