Angular - Post request failing to download pdf file - asp.net

Question

I am trying to do a POST request to download a pdf file from the sever. The error I get is message: "Http failure during parsing". I'm not sure why it would work for a GET request but not for a POST request or I am missing something.
this.httpClient.post(url, {
responseType: 'blob' as 'json',
observe: 'response'
})
.pipe(take(1))
.subscribe((data:HttpResponse<Blob>) => {
const blob = new Blob([data.body], { type: 'application/pdf' });
saveAs(blob, 'test.pdf');
});
However if I do a GET request, it seems to work.
this.httpClient.get<Blob>(url,
{
observe: 'response',
responseType: (('blob') as any) as 'json'
})
.pipe(take(1))
.subscribe(
(response: HttpResponse<Blob>) => {
const blob = new Blob([response.body], { type: mediaType });
saveAs(blob, 'Report.pdf');
},
(error: any) => {
console.error(error);
}
);
Server
[HttpPost]
[Route("download/{id}")]
public IHttpActionResult DownloadPdf()
{
var buffer = _test.RenderDrawing();
var result = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new ByteArrayContent(buffer)
};
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = $"Test.pdf"
};
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
return ResponseMessage(result);
}

Answer 1

In you post request, you are defining types differently. try something like this:
this.httpClient.post(url, {
responseType: 'blob',
observe: 'response'
})
.pipe(take(1))
.subscribe((data:HttpResponse<Blob>) => {
const blob = new Blob([data.body], { type: 'application/pdf' });
saveAs(blob, 'test.pdf');
});