C# Setting custom headers to httpclient gives error as misused header name-CodePudding

I am trying to set custom headers like these

x-my-header:somecustomval
content-type:application/vnd.status json
.
.
.
other headers

There are two approaches I tried, using a dictionary of headers

_httpClient.DefaultRequestHeaders.Clear();

foreach (var h in headers)
{
  _httpClient.DefaultRequestHeaders.Add(h.Key.ToString(), h.Value.ToString());
}

HttpRequestMessage req = new HttpRequestMessage();

foreach (var h in headers)
{
  req.Headers.Add(h.Key.ToString(), h.Value.ToString());
}

The error I am getting in both approaches is this:

Misused header name. Make sure request headers are used with HttpRequestMessage, response headers with HttpResponseMessage, and content headers with HttpContent objects.

How do you set the headers for a POST in the HttpClient in C# net core 3.1? Can you not set custom headers?

CodePudding user response：

Use the HttpHeaders.TryAddWithoutValidation method in either of your attempts.

Internally the default HttpHeaders.Add will try to validate that you are adding a known HTTP header and will fail if not valid.

Reference HttpHeaders