To override the Content-type in your clients, use the HTTP Accept Header, append  the .xml suffix or  ?format=xml
        
        HTTP + XML
         The following are sample HTTP requests and responses. 
            The placeholders shown need to be replaced with actual values.
DELETE /invoices/{InvoiceId} HTTP/1.1 
Host: blazor-gallery.servicestack.net 
Accept: application/xml
 
HTTP/1.1 200 OK
Content-Type: application/xml
Content-Length: length
<IdResponse xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.servicestack.net/types">
  <Id>String</Id>
  <ResponseStatus>
    <ErrorCode>String</ErrorCode>
    <Message>String</Message>
    <StackTrace>String</StackTrace>
    <Errors>
      <ResponseError>
        <ErrorCode>String</ErrorCode>
        <FieldName>String</FieldName>
        <Message>String</Message>
        <Meta xmlns:d5p1="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
          <d5p1:KeyValueOfstringstring>
            <d5p1:Key>String</d5p1:Key>
            <d5p1:Value>String</d5p1:Value>
          </d5p1:KeyValueOfstringstring>
        </Meta>
      </ResponseError>
    </Errors>
    <Meta xmlns:d3p1="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
      <d3p1:KeyValueOfstringstring>
        <d3p1:Key>String</d3p1:Key>
        <d3p1:Value>String</d3p1:Value>
      </d3p1:KeyValueOfstringstring>
    </Meta>
  </ResponseStatus>
</IdResponse>