EWS HttpHeader内容类型

Question

I've followed Microsoft's Get started with EWS Managed API client applications tutorial, in an effort to build an application that will get specific items from a mailbox on an Exchange server.

It seems that after the initial auto-discover operations succeed, no matter what kind of request I send through the API, I get a response back containing the following:

HTTP/1.1 415 Cannot process the message because the content type 'text/plain; charset=utf-8' was not the expected type 'text/xml; charset=utf-8'.

With Microsoft.Exchange.WebServices.Data.ExchangeService.TraceEnabled = true , the trace of a typical request looks like this (this one is generated by calling Folder.Bind(service, "IT", propSet) ):

<?xml version="1.0" encoding="utf-16"?>
<Trace Tag="EwsRequest" Tid="1" Time="2019-03-01 14:42:02Z" Version="15.0.913.15">
  <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
    <soap:Header>
      <t:RequestServerVersion Version="Exchange2013" />
    </soap:Header>
    <soap:Body>
      <m:GetFolder>
        <m:FolderShape>
          <t:BaseShape>IdOnly</t:BaseShape>
        </m:FolderShape>
        <m:FolderIds>
          <t:FolderId Id="IT" />
        </m:FolderIds>
      </m:GetFolder>
    </soap:Body>
  </soap:Envelope>
</Trace>

It looks like the Content-Type header is missing altogether, so the server sees the request as text/plain; charset=utf-8 text/plain; charset=utf-8 . It shouldn't be a problem to add Content-Type: text/xml; charset=utf-8 Content-Type: text/xml; charset=utf-8 to requests that the ExchangeService object makes, but the member Dictionary HttpHeaders is not settable (see the interface in ExchangeServiceBase ).

Any idea how I can either send the server an acceptable request with the EWS Managed API, or configure the target Exchange server so that it accepts the requests I'm sending? I've come across lots of related SO questions, but none with an actual answer to this problem.

Answer 1

I was getting the same error and the only clue I could find was this thread.

I eventually fixed it by switching to Microsoft.Exchange.WebServices.NETStandard -v 1.1.3 (from -v 2.0.0-beta1).