为什么WebAPI抛出'没有MediaTypeFormatter'错误

我的WebAPI控制器出现了一个奇怪的问题。

在我的开发环境(Win7, IIS 7.5)中，控制器上的方法被调用，结果按预期返回。

在我的集成环境(WIn Server 2003, IIS 6.0)中，我通过将代码从开发盒复制到集成盒来部署代码。控制器上的方法被调用并返回以下错误:

"没有MediaTypeFormatter可用于读取"EmailQueueResult"类型的对象"来自媒体类型为"text/html"的内容。"

我不明白的是为什么我只在集成环境中得到这个错误，而不是在开发环境中。

    public HttpResponseMessage Post([FromBody]EmailQueueMessage email)
    {
        EmailQueueResult result;
        if (email != null)
        {
            try
            {
                var emailQueueIdList = QueueEmails(email);
                QueueAttachments(email, emailQueueIdList);
                foreach(var emailQueueId in emailQueueIdList)
                {
                    UpdateEmailQueueDateQueued(emailQueueId, DateTime.Now);
                }
                result = new EmailQueueResult(0, "Email added to queue.", "", null);
            }
            catch (Exception e) {
                result = new EmailQueueResult(2, "Error occurred.", e.Message, null);
            }
        }
        else
        {
            result = new EmailQueueResult(1, "Email passed in was null.", "", null);
        }
        return ControllerContext.Request.CreateResponse(HttpStatusCode.OK, result, "application/json");
    }

WebApiConfig.cs:

namespace App_Start
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.Routes.MapHttpRoute(
                "ControllerWithBooleanParameter",
                "api/{controller}/{showSentEmails}",
                null,
                new { boolConstraint = new IsBoolean() }
            );
            config.Routes.MapHttpRoute(
                "ControllerWithIntegerParameter",
                "api/{controller}/{id}",
                null,
                new { id = @"^'d+$" }
            );
            config.Routes.MapHttpRoute(
                "Default",
                "api/{controller}/{id}",
                new { id = UrlParameter.Optional }
            );
        }
    }
}

web . config:

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
    <appSettings>
        <add key="webpages:Version" value="2.0.0.0" />
        <add key="webpages:Enabled" value="false" />
        <add key="PreserveLoginUrl" value="true" />
        <add key="ClientValidationEnabled" value="true" />
        <add key="UnobtrusiveJavaScriptEnabled" value="true" />
    </appSettings>
    <system.net>
        <settings>
            <httpWebRequest useUnsafeHeaderParsing="true" />
        </settings>
        <mailSettings>
            <smtp from="address@email.com">
                <network host="smtp.server.com" port="25" />
            </smtp>
        </mailSettings>
    </system.net>
    <system.web>
        <compilation debug="true" targetFramework="4.0" />
        <authentication mode="None" />
        <pages>
            <namespaces>
                <add namespace="System.Web.Helpers" />
                <add namespace="System.Web.Mvc" />
                <add namespace="System.Web.Mvc.Ajax" />
                <add namespace="System.Web.Mvc.Html" />
                <add namespace="System.Web.Optimization" />
                <add namespace="System.Web.Routing" />
                <add namespace="System.Web.WebPages" />
            </namespaces>
        </pages>
    </system.web>
    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <modules runAllManagedModulesForAllRequests="true" />
        <handlers>
            <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
            <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
            <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
            <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%'Microsoft.NET'Framework'v4.0.30319'aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
            <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%'Microsoft.NET'Framework64'v4.0.30319'aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
            <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
        </handlers>
    </system.webServer>
    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
                <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
                <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
                <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
            </dependentAssembly>
        </assemblyBinding>
    </runtime>
</configuration>

我也试过让这个方法只是返回一个直接的EmailQueueResult，这给了我相同的结果。

编辑:下面是我尝试的一些测试以及它们的结果:

• 当我使用外部工具向本地机器上的web服务发送POST请求时，它会按预期工作。
• 当我使用本地代码副本执行调用web服务的代码时，它按预期工作。
• 当我使用外部工具向集成机器上的web服务发送POST请求时，它会按预期工作。
• 当我使用集成机执行调用web服务的代码时，我得到上述错误。

发送POST的代码行:

        EmailQueueResult result = PostToWebService<EmailQueueMessage, EmailQueueResult>(EmailQueueBaseAddress, "application/json", EmailQueueUrlToCall, emailQueueMessage);

实际调用的PostToWebService方法:

    protected returnType PostToWebService<dataType, returnType>(string baseAddress, string mediaType, string urlToCall, dataType data)
    {
        HttpClient client = new HttpClient();
        client.BaseAddress = new Uri(baseAddress);
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(mediaType));
        MediaTypeFormatter jsonFormatter = new JsonMediaTypeFormatter();
        HttpContent content = new ObjectContent<dataType>(data, jsonFormatter);
        HttpResponseMessage response = client.PostAsync(urlToCall, content).Result;
        returnType result = response.Content.ReadAsAsync<returnType>().Result;
        return result;
    }

UPDATE:我将网站和web服务安装在2008年的服务器上。唯一失败的组合似乎是从2003机器上的网站调用2003机器上的web服务(2003站点-> 2003服务)。其他三种组合(2008站点-> 2008服务，2008站点-> 2003服务，2003站点-> 2008服务)似乎都能正常工作。