服务器错误：请求已中止：无法创建SSL / TLS安全通道(Server Error: The request was aborted: Could not create SSL/TLS secure channel)

 我收到错误The request was aborted: Could not create SSL/TLS secure channel. 根据cloudflare上的https端点请求。 
 
 码： 
 
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
    var wc = new WebClient();
    var json = wc.DownloadString("https://cloudflare.com");
    Console.Write(json);
 
 这是Stack上常见的问题，其中将ServicePoint设置为TLS12可以修复它。 这在我当地修复了它。 但是每当我将代码提升到服务器时，错误就会回来（我很肯定我已经应用了代码更改。）如果我删除了https并使用http，它可以正常工作。 
 
 经过大量的搜索，我发现了这个KB： https ： //support.microsoft.com/en-us/kb/3109853我在Server1上安装了它，并没有解决问题。 
 
 谁知道还有什么可以尝试？ 必须有一些关于导致此问题的服务器环境。 它是.Net修复/安全更新的最新版本。 
 
[WebException: The request was aborted: Could not create SSL/TLS secure channel.]
   System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult) +823
   System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar) +84

[HttpRequestException: An error occurred while sending the request.]
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +181
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +66
   System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +30
   TrackerBase.Controllers.<Verify>d__0.MoveNext() +535
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +181
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +66
   System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +30
   lambda_method(Closure , Task ) +40
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +76
   System.Web.Mvc.Async.<>c__DisplayClass3f.<BeginInvokeAsynchronousActionMethod>b__3e(IAsyncResult asyncResult) +21
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +80
   System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +386
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +30
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +185
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +900
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +1299
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +43
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +38
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +38
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +18

I'm getting the error The request was aborted: Could not create SSL/TLS secure channel. on a request being made to a https endpoint on cloudflare. 
 
Code:
 
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
    var wc = new WebClient();
    var json = wc.DownloadString("https://cloudflare.com");
    Console.Write(json);
 
This is a commonly asked question on Stack, where setting the ServicePoint to TLS12 fixes it. That fixes it for me locally. However whenever I promote the code to the Server, the error comes back (and I'm positive my code changes have been applied.) If I remove the https and use http it works fine. 
 
After tons of searching I found this KB: https://support.microsoft.com/en-us/kb/3109853 Which I installed on Server1, and it did not fix the problem.
 
Anyone know what else to try? There must be something about the Server environment that is causing this. It's up to date on .Net fixes/security updates.
 
[WebException: The request was aborted: Could not create SSL/TLS secure channel.]
   System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult) +823
   System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar) +84

[HttpRequestException: An error occurred while sending the request.]
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +181
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +66
   System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +30
   TrackerBase.Controllers.<Verify>d__0.MoveNext() +535
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +181
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +66
   System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +30
   lambda_method(Closure , Task ) +40
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +76
   System.Web.Mvc.Async.<>c__DisplayClass3f.<BeginInvokeAsynchronousActionMethod>b__3e(IAsyncResult asyncResult) +21
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +80
   System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +386
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +30
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +185
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +900
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +1299
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +43
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +38
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +38
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +18

原文：https://stackoverflow.com/questions/38042382