C# 取消任务会导致ObjectDisposedException

在我的Xamarin iOS应用程序中，我有一种方法可以将用户配置文件数据和配置文件图像上传到服务器。看起来是这样的：

public async Task UploadProfileAndImage（ProfileInputModel配置文件、映像映像、操作完成）
{
如果（AreProfileAndImageBeingUploaded（））{
取消ProfileAndImageUpload（）；
}
如果（完成！=null）{
_uploadCallbacks.Add（完成）；
}
_uploadCancellationSource=新的CancellationTokenSource（）；
var tasks=new list发布
CancelProfileAndImageUpload
的代码我已经在代码示例的底部添加了它，所以它在ProfileApi方法中失败了，在这里显示它们会很有用。如何处理这些方法中的取消令牌很重要。@MarcinKuptel:你能发布一个其他方法可以复制的最小示例吗运行？包含异常的堆栈跟踪也会很有帮助。
System.ObjectDisposedException: The object was used after being disposed.  

    2015-06-25 00:35:11.075 Example[2713:111447] System.ObjectDisposedException: The object was used after being disposed.
  at System.Net.WebConnection.EndWrite (System.Net.HttpWebRequest request, Boolean throwOnError, IAsyncResult result) [0x0002c] in //Library/Frameworks/Xamarin.iOS.framework/Versions/8.10.1.64/src/mono/mcs/class/System/System.Net/WebConnection.cs:1071 
  at System.Net.WebConnectionStream.WriteAsyncCB (IAsyncResult r) [0x00013] in //Library/Frameworks/Xamarin.iOS.framework/Versions/8.10.1.64/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:458 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:477 
  at System.Net.Http.HttpClientHandler+<SendAsync>c__async0.MoveNext () [0x002f4] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:344 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.CookieAwareMessageHandler+<SendAsync>c__async0.MoveNext () [0x00115] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/CookeAwareMessageHandler.cs:30 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:580 
  at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:274 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.ProfileApi+<SetProfilePicture>c__async0.MoveNext () [0x000df] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/ProfileApi.cs:23 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[Shared.ApiResponse[]].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.ProfileDownloader+<UploadProfileAndImage>c__async0.MoveNext () [0x0013e] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/ProfileDownloader.cs:57 
System.ObjectDisposedException: The object was used after being disposed.
  at System.Net.WebConnection.EndWrite (System.Net.HttpWebRequest request, Boolean throwOnError, IAsyncResult result) [0x0002c] in //Library/Frameworks/Xamarin.iOS.framework/Versions/8.10.1.64/src/mono/mcs/class/System/System.Net/WebConnection.cs:1071 
  at System.Net.WebConnectionStream.WriteAsyncCB (IAsyncResult r) [0x00013] in //Library/Frameworks/Xamarin.iOS.framework/Versions/8.10.1.64/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:458 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:477 
  at System.Net.Http.HttpClientHandler+<SendAsync>c__async0.MoveNext () [0x002f4] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:344 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.CookieAwareMessageHandler+<SendAsync>c__async0.MoveNext () [0x00115] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/CookeAwareMessageHandler.cs:30 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:580 
  at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:274 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.ProfileApi+<SetProfilePicture>c__async0.MoveNext () [0x000df] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/ProfileApi.cs:23 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:201 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
  at System.Runtime.CompilerServices.TaskAwaiter`1[Shared.ApiResponse[]].GetResult () [0x00000] in /Users/builder/data/lanes/1503/e6ebd18b/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:372 
  at Shared.ProfileDownloader+<UploadProfileAndImage>c__async0.MoveNext () [0x0013e] in /Users/mku/Documents/Private projects/Xamarin/Example/Shared/ProfileDownloader.cs:57