執行 API Controller 遇到 「Not running in a hosted service or the Development Fabric.」 問題之解決方案

建置 API Controller 時，執行後遇到以下錯誤訊息：

Not running in a hosted service or the Development Fabric.

描述: 在執行目前 Web 要求的過程中發生未處理的例外狀況。請檢閱堆疊追蹤以取得錯誤的詳細資訊，以及在程式碼中產生的位置。

例外狀況詳細資訊: System.InvalidOperationException: Not running in a hosted service or the Development Fabric.

原始程式錯誤:

在執行目前 Web 要求期間，產生未處理的例外狀況。如需有關例外狀況來源與位置的資訊，可以使用下列的例外狀況堆疊追蹤取得。

堆疊追蹤:

[InvalidOperationException: Not running in a hosted service or the Development Fabric.]
   Microsoft.WindowsAzure.Diagnostics.DiagnosticMonitor.GetDefaultStartupInfoForCurrentRoleInstance() +173
   Microsoft.WindowsAzure.Diagnostics.DiagnosticMonitorTraceListener..ctor() +59

[ConfigurationErrorsException: 無法建立 Microsoft.WindowsAzure.Diagnostics.DiagnosticMonitorTraceListener, Microsoft.WindowsAzure.Diagnostics, Version=2.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35。]
   System.Diagnostics.TraceUtils.GetRuntimeObject(String className, Type baseType, String initializeData) +6707013
   System.Diagnostics.TypedElement.BaseGetRuntimeObject() +45
   System.Diagnostics.ListenerElement.GetRuntimeObject() +83
   System.Diagnostics.ListenerElementsCollection.GetRuntimeObject() +142
   System.Diagnostics.TraceInternal.get_Listeners() +181
   System.Diagnostics.TraceInternal.TraceEvent(TraceEventType eventType, Int32 id, String format, Object[] args) +155
   System.Diagnostics.Trace.TraceInformation(String message) +14
   System.Web.Http.Tracing.SystemDiagnosticsTraceWriter.TraceMessage(TraceLevel level, String message) +157
   System.Web.Http.Tracing.SystemDiagnosticsTraceWriter.Trace(HttpRequestMessage request, String category, TraceLevel level, Action`1 traceAction) +438
   System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEndAsync(ITraceWriter traceWriter, HttpRequestMessage request, String category, TraceLevel level, String operatorName, String operationName, Action`1 beginTrace, Func`1 execute, Action`2 endTrace, Action`1 errorTrace) +464
   System.Web.Http.Tracing.Tracers.RequestMessageHandlerTracer.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) +367
   System.Net.Http.DelegatingHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) +41
   System.Web.Http.HttpServer.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) +390
   System.Net.Http.HttpMessageInvoker.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) +55
   System.Web.Http.WebHost.HttpControllerHandler.BeginProcessRequest(HttpContextBase httpContextBase, AsyncCallback callback, Object state) +316
   System.Web.Http.WebHost.HttpControllerHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +77
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +301
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

這因為是 Windows Azure 雲端服務專案發生的情況，所以解決方法有二：

1.

建置 Windows Azure 雲端服務會有兩個專案，一為 ASP.NET MVC 4 Web 應用程式，另一個是 Windows Azure Web Role 專案。必須在方案內設定 Windows Azure Web Role 專案為「啟用」，像我就是設定 ASP.NET MVC 4 Web 應用程式 為「啟用」。

2.

web.config 中移除追蹤接聽項 ( trace listener )：

<trace>
  <listeners>
    <add type="Microsoft.WindowsAzure.Diagnostics.DiagnosticMonitorTraceListener, Microsoft.WindowsAzure.Diagnostics, Version=2.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
      name="AzureDiagnostics">
      <filter type="" />
    </add>
  </listeners>
</trace>  

兩種方法都能解決此種問題，我是用第二種方法解決。