C# HttpClient请求引发IOException

以下代码抛出IOException，并显示消息：“指定的注册表项不存在。”

这只是在一个主控制台应用程序。看起来错误是由mscorlib.dll引发的！Microsoft.Win32.RegistryKey.Win32错误（int errorCode，string str）。我不知道为什么会抛出这个错误，也不知道如何开始调试它

编辑堆栈跟踪：

位于Microsoft.Win32.RegistryKey.Win32错误（Int32错误代码，字符串str）

只有一行，没有内部异常等

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]  

mscorlib.dll！Microsoft.Win32.RegistryKey.Win32错误（int errorCode，string str）+0x189字节
mscorlib.dll！Microsoft.Win32.RegistryKey.GetValueKind（字符串名称）+0x7f字节
System.dll！System.Net.HybridWebProxyFinder.InitializeFallbackSettings（）+0x9e字节
[本机到托管转换]
[管理到本机转换]
System.dll！System.Net.AutoWebProxyScriptEngine.AutoWebProxyScriptEngine（System.Net.WebProxy代理，bool useRegistry）+0xd0字节
System.dll！System.Net.WebProxy.UnsafeUpdateFromRegistry（）+0x2c字节
System.dll！System.Net.Configuration.DefaultProxySectionInternal.DefaultProxySectionInternal（System.Net.Configuration.DefaultProxySection节）+0x1d8字节
System.dll！System.Net.Configuration.DefaultProxySectionInternal.GetSection（）+0xec字节
System.dll！System.Net.WebRequest.InternalDefaultWebProxy.get（）+0xcc字节
System.dll！System.Net.HttpWebRequest.HttpWebRequest（System.Uri Uri，System.Net.ServicePoint ServicePoint）+0xdf字节
System.dll！System.Net.HttpWebRequest.HttpWebRequest（System.Uri Uri，bool returnResponseOnFailureStatusCode，string connectionGroupName，System.Action resendRequestContent）+0x2b字节
System.Net.Http.dll！System.Net.Http.HttpClientHandler.CreateAndPrepareWebRequest（System.Net.Http.HttpRequestMessage请求）+0x59字节
System.Net.Http.dll！System.Net.Http.HttpClientHandler.SendAsync（System.Net.Http.HttpRequestMessage请求，System.Threading.CancellationToken CancellationToken）+0xf4字节
System.Net.Http.dll！System.Net.Http.HttpMessageInvoker.SendAsync（System.Net.Http.HttpRequestMessage请求，System.Threading.CancellationToken CancellationToken）+0x4f字节
System.Net.Http.dll！System.Net.Http.HttpClient.SendAsync（System.Net.Http.HttpRequestMessage请求，System.Net.Http.HttpCompletionOption completionOption，System.Threading.CancellationToken CancellationToken）+0x13e字节
System.Net.Http.dll！System.Net.Http.HttpClient.GetAsync（System.Uri requestUri，System.Net.Http.HttpCompletionOption completionOption）+0xc字节
ConsoleServiceTest.exe！ConsoleServiceTest.Program.Main（字符串[]args）行20+0x17字节C#
[本机到托管转换]
[管理到本机转换]
Microsoft.VisualStudio.HostingProcess.Utilities.dll！Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）+0x5a字节
mscorlib.dll！System.Threading.ExecutionContext.RunInternal（System.Threading.ExecutionContext ExecutionContext，System.Threading.ContextCallback回调，对象状态，bool preserveSyncCtx）+0x285字节
mscorlib.dll！System.Threading.ExecutionContext.Run（System.Threading.ExecutionContext ExecutionContext，System.Threading.ContextCallback回调，对象状态，bool preserveSyncCtx）+0x9字节
mscorlib.dll！System.Threading.ExecutionContext.Run（System.Threading.ExecutionContext ExecutionContext，System.Threading.ContextCallback回调，对象状态）+0x57字节
mscorlib.dll！System.Threading.ThreadHelper.ThreadStart（）+0x51字节
[本机到托管转换]

无论出于何种原因，您的

HttpClient

代码正在注册表中查找代理设置，无法打开该项。查看代码显示它试图打开HKCU，然后按顺序转到以下键之一：

“HKCU\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Internet设置\\连接”

“HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Internet设置\\连接”

“HKLM\\SOFTWARE\\Policys\\Microsoft\\Windows\\CurrentVersion\\Internet设置”

这三者之一可能是您的流程无法访问的关键，为什么我不确定。一种可能的修复方法是禁用自动检测代理设置

否则，您将需要准确地了解它正在加载的键，我们将通过两个步骤来完成

下载并运行Procmon，对应用程序的注册表访问进行筛选，如下所示：

打开后，如果启用，则禁用捕获（放大镜上应有一个红色的X）

开始筛选进程名称

取消选择除注册表项以外的所有选项

启用捕获（单击放大镜）

运行应用程序

在日志中找到有问题的条目，双击查看它打开的键

---

一旦确定了有问题的密钥，就可以找出应用程序无法访问该密钥的原因。如果您的应用程序名称有任何迹象表明，您的服务运行所使用的用户帐户可能无法访问注册表项。

这似乎是由于.NET Framework最近的安全更新造成的：

这一切归结为web代理解析中的以下代码：

[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)
    {
    }
}

正如您所见，它检查KB文章中提到的特定注册表项。您还应该注意，异常是在内部捕获的，但是您看到它是因为您在VisualStudio的调试选项中启用了第一次机会异常

如果不希望看到此异常，则应添加值为

0

的指定注册表项：

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

对于64位计算机上的32位进程：

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

---

我同意Ligaz的回答，我已经记录了一个关于这个bug的连接问题：

将以下内容保存到.reg文件中

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

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