HttpClient的请求抛出IOException异常(HttpClient request th

下面的代码抛出与消息一个IOException异常：“指定的注册表项不存在。”

HttpClient client = new HttpClient();

Uri uri = new Uri("http://www.google.com");

client.GetAsync(uri);

这仅仅是在主控制台应用程序。它看起来像正在被抛出的mscorlib.dll错误！Microsoft.Win32.RegistryKey.Win32Error（INT的errorCode，字符串str）。我不知道为什么被抛出此错误或如何开始调试它。

编辑堆栈跟踪：

在Microsoft.Win32.RegistryKey.Win32Error（的Int32的errorCode，字符串str）

这只是1行，没有内exxception等。

调用堆栈是：

mscorlib.dll!Microsoft.Win32.RegistryKey.Win32Error(int errorCode, string str) + 0x189 bytes    
mscorlib.dll!Microsoft.Win32.RegistryKey.GetValueKind(string name) + 0x7f bytes 
System.dll!System.Net.HybridWebProxyFinder.InitializeFallbackSettings() + 0x9e bytes    
[Native to Managed Transition]  
[Managed to Native Transition]  
System.dll!System.Net.AutoWebProxyScriptEngine.AutoWebProxyScriptEngine(System.Net.WebProxy proxy, bool useRegistry) + 0xd0 bytes   
System.dll!System.Net.WebProxy.UnsafeUpdateFromRegistry() + 0x2c bytes  
System.dll!System.Net.Configuration.DefaultProxySectionInternal.DefaultProxySectionInternal(System.Net.Configuration.DefaultProxySection section) + 0x1d8 bytes 
System.dll!System.Net.Configuration.DefaultProxySectionInternal.GetSection() + 0xec bytes   
System.dll!System.Net.WebRequest.InternalDefaultWebProxy.get() + 0xcc bytes 
System.dll!System.Net.HttpWebRequest.HttpWebRequest(System.Uri uri, System.Net.ServicePoint servicePoint) + 0xdf bytes  
System.dll!System.Net.HttpWebRequest.HttpWebRequest(System.Uri uri, bool returnResponseOnFailureStatusCode, string connectionGroupName, System.Action<System.IO.Stream> resendRequestContent) + 0x2b bytes  
System.Net.Http.dll!System.Net.Http.HttpClientHandler.CreateAndPrepareWebRequest(System.Net.Http.HttpRequestMessage request) + 0x59 bytes   
System.Net.Http.dll!System.Net.Http.HttpClientHandler.SendAsync(System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) + 0xf4 bytes  
System.Net.Http.dll!System.Net.Http.HttpMessageInvoker.SendAsync(System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) + 0x4f bytes 
System.Net.Http.dll!System.Net.Http.HttpClient.SendAsync(System.Net.Http.HttpRequestMessage request, System.Net.Http.HttpCompletionOption completionOption, System.Threading.CancellationToken cancellationToken) + 0x13e bytes 
System.Net.Http.dll!System.Net.Http.HttpClient.GetAsync(System.Uri requestUri, System.Net.Http.HttpCompletionOption completionOption) + 0xc bytes   

ConsoleServiceTest.exe!ConsoleServiceTest.Program.Main(string[] args) Line 20 + 0x17 bytes  C#
    [Native to Managed Transition]  
    [Managed to Native Transition]  
    Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() + 0x5a bytes  
    mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x285 bytes 
    mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x9 bytes   
    mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x57 bytes    
    mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x51 bytes   
    [Native to Managed Transition]

Answer 1:

看来，这是.NET Framework的一个最近的安全更新造成的： MS12-074：.NET Framework中的漏洞可能允许远程执行代码：2012年11月13日（KB 2745030）

这一切都归结到Web代理解析如下代码：

[RegistryPermission(SecurityAction.Assert, Read=@"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework")]
private static void InitializeFallbackSettings()
{
    allowFallback = false;
    try
    {
        using (RegistryKey key = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\.NETFramework"))
        {
            try
            {
                if (key.GetValueKind("LegacyWPADSupport") == RegistryValueKind.DWord)
                {
                    allowFallback = ((int) key.GetValue("LegacyWPADSupport")) == 1;
                }
            }
            catch (UnauthorizedAccessException)
            {
            }
            catch (IOException)
            {
            }
        }
    }
    catch (SecurityException)
    {
    }
    catch (ObjectDisposedException)
    {
    }
}

正如你可以看到它会检查知识库文章中提到特定的注册表项。你还应该注意的是，除了在内部抓住了，但你看到它，因为你已经在Visual Studio中的调试选项启用的第一次机会异常。

如果你想不看到这个异常应添加同值指定的注册表键0 ：

Registry location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework  
DWORD (32-bit) Value name: LegacyWPADSupport
Value data: 0

和用于在64位机器32位进程：

Registry location: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework
DWORD (32-bit) Value name: LegacyWPADSupport
Value data: 0

Answer 2:

我同意Ligaz的答案，我已经记录有关此错误的一个连接问题： https://connect.microsoft.com/VisualStudio/feedback/details/773666/webrequest-create-eats-an-ioexception-on-the-首次呼叫＃细节

保存以下到一个.reg文件，并导入到注册表，以防止此错误被提出：

Windows Registry Editor Version 5.00

; The following value prevents an IOException from being thrown and caught
; by System.Net.HybridWebProxyFinder.InitializeFallbackSettings() (in System.dll)
; when WebRequest.Create is first called.  By default the "LegacyWPADSupport"
; value doesn't exist, and when InitializeFallbackSettings calls GetValueKind,
; an IOException is thrown.  This adds the value with its default of false to
; prevent the exception.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework]
"LegacyWPADSupport"=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework]
"LegacyWPADSupport"=dword:00000000

Answer 3:

无论出于何种原因，你HttpClient代码正在寻找在注册表中的代理服务器设置而无法打开的关键。一看通过代码表明，它试图打开HKCU然后去为了以下项之一：

"HKCU\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Internet Settings\\Connections"
"HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Internet Settings\\Connections"
"HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"

其中这三个潜在关键的进程有没有访问权限，为什么我不知道。一个可能的解决办法是禁用自动检测代理设置。

否则，你需要弄清楚到底哪些关键的它加载，我们将做到这一点有两个步骤。