.NET Framework 4.8对接巴西Itaú银行API遇SSL/TLS安全通道创建失败

我正在对接巴西Itaú银行的API，需完成认证后才能执行后续操作。但将项目部署到Windows Server 2019标准版的IIS后，.NET Framework 4.8项目触发异常："请求已中止: 无法创建SSL/TLS安全通道。"

项目为VB.NET WebForms架构，包含一个.NET Framework 4.8项目和一个.NET Framework 2.0项目，4.8项目引用2.0项目。本地使用Visual Studio 2022调试完全正常，但发布到服务器后卡在认证环节。

服务器已安装.NET Framework 4.8运行时，IIS应用池的.NET CLR版本设置为4.0.30319。我尝试了两种请求发送方式，均出现相同错误，相关代码及异常栈信息如下：

.NET Framework 2.0相关代码 #

Public Sub New()
    ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate)
    ServicePointManager.SecurityProtocol = CType(&HC00, Net.SecurityProtocolType)
End Sub

Public Function ValidateServerCertificate(ByVal sender As Object, ByVal certificate As X509Certificate, ByVal chain As X509Chain, ByVal sslPolicyErrors As SslPolicyErrors) As Boolean
    Return True
End Function

.NET Framework 4.8认证代码（HttpClient方式） #

Private ReadOnly Property Certificado As X509Certificate2
    Get
        If m_Certificado Is Nothing Then
            Dim assembly As Assembly = Assembly.GetExecutingAssembly()
            Using stream As Stream = assembly.GetManifestResourceStream(GetType(AppModule), "certificado.pfx")
                If stream Is Nothing Then
                    Throw New ApplicationException("Certificado não encontrado.")
                End If

                Dim rawData(CInt(stream.Length)) As Byte
                stream.Read(rawData, 0, rawData.Length)

                m_Certificado = New X509Certificate2(rawData, "PASSWORD")
            End Using
        End If
        Return m_Certificado
    End Get
End Property

Public Function EnviarAutenticacao() As RetornoRequisicao
    Dim handler As New WebRequestHandler()
    Dim httpContent As StringContent = Nothing
    Dim responseMessage As HttpResponseMessage = Nothing
    Dim resposta As New RetornoRequisicao
    Dim sClient As String = ""

    Dim contentData As String = "grant_type=client_credentials&client_id=CLIENT_ID&client_secret=CLIENT_SECRET"

    Try
        handler.ClientCertificates.Add(Certificado)
        'With the 2 lines below, removing them from the constructor or leaving them in the constructor and removing from here
        handler.SslProtocols = System.Security.Authentication.SslProtocols.Tls12
        handler.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate)

        Using client As New HttpClient(handler)
            Try
                httpContent = New StringContent(contentData, TextEncoding, "application/x-www-form-urlencoded")

                responseMessage = client.PostAsync(URLAutenticacao, httpContent).GetAwaiter().GetResult()

                If responseMessage.IsSuccessStatusCode Then
                    resposta.Status = CInt(HttpStatusCode.OK)
                Else
                    resposta.Status = CInt(responseMessage.StatusCode)
                End If
                resposta.Conteudo = responseMessage.Content.ReadAsStringAsync().GetAwaiter().GetResult()

            Finally
                Try
                    sClient = JsonConvert.SerializeObject(client, ErrorSerializerSettings)
                Catch
                End Try
            End Try
        End Using

    Catch ex As Exception
        Dim sbMensagem As New StringBuilder

        sbMensagem.AppendLine("Erro ao Autenticar")

        Try
            sbMensagem.AppendLine($"Handler:{vbCrLf}{JsonConvert.SerializeObject(handler, ErrorSerializerSettings)}")
        Catch
        End Try
        If Not String.IsNullOrEmpty(sClient) Then
            sbMensagem.AppendLine($"Client:{vbCrLf}{sClient}")
        End If
        Try
            sbMensagem.AppendLine($"Certificate:{vbCrLf}{JsonConvert.SerializeObject(Certificado, ErrorSerializerSettings)}")
        Catch
        End Try
        If Not String.IsNullOrEmpty(contentData) Then
            sbMensagem.AppendLine($"Content Data:{vbCrLf}{contentData}")
        End If
        If httpContent IsNot Nothing Then
            Try
                sbMensagem.AppendLine($"Http Content:{vbCrLf}{JsonConvert.SerializeObject(httpContent, ErrorSerializerSettings)}")
            Catch
            End Try
        End If
        If responseMessage IsNot Nothing Then
            Try
                sbMensagem.AppendLine($"Response Message:{vbCrLf}{JsonConvert.SerializeObject(responseMessage, ErrorSerializerSettings)}")
            Catch
            End Try
        End If
        Try
            sbMensagem.AppendLine($"Resposta:{vbCrLf}{JsonConvert.SerializeObject(resposta, ErrorSerializerSettings)}")
        Catch
        End Try

        Throw New ApplicationException(sbMensagem.ToString, ex)
    End Try

    Return resposta
End Function

.NET Framework 4.8认证代码（HttpWebRequest方式） #

Protected Overrides Function EnviarAutenticacao() As RetornoRequisicao
    Dim request As HttpWebRequest = Nothing
    Dim requestResponse As HttpWebResponse = Nothing
    Dim resposta As New RetornoRequisicao

    Try
        request = CType(WebRequest.Create(URLAutenticacao), HttpWebRequest)
        request.ContentType = "application/x-www-form-urlencoded"
        request.Method = TipoEnvioAutenticacao
        request.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate)

        Dim dataBody As String = "grant_type=client_credentials&client_id=CLIENT_ID&client_secret=CLIENT_SECRET"
        Dim body As Byte() = Encoding.ASCII.GetBytes(dataBody)
        request.ContentLength = body.Length

        Dim myWriter As Stream = Nothing
        request.ClientCertificates.Add(Certificado)

        myWriter = request.GetRequestStream()
        myWriter.Write(body, 0, body.Length)

        requestResponse = CType(request.GetResponse(), HttpWebResponse)
        resposta.Conteudo = New StreamReader(requestResponse.GetResponseStream()).ReadToEnd()

        If requestResponse.StatusCode >= 200 AndAlso requestResponse.StatusCode <= 299 Then
            resposta.Status = CInt(HttpStatusCode.OK)
        Else
            resposta.Status = CInt(requestResponse.StatusCode)
        End If

    Catch ex As Exception
        Dim sbMensagem As New StringBuilder

        sbMensagem.AppendLine("Erro ao Autenticar")

        Try
            sbMensagem.AppendLine($"Request:{vbCrLf}{JsonConvert.SerializeObject(request, ErrorSerializerSettings)}")
        Catch
        End Try
        If requestResponse IsNot Nothing Then
            Try
                sbMensagem.AppendLine($"Request Response:{vbCrLf}{JsonConvert.SerializeObject(requestResponse, ErrorSerializerSettings)}")
            Catch
            End Try
        End If
        Try
            sbMensagem.AppendLine($"Resposta:{vbCrLf}{JsonConvert.SerializeObject(resposta, ErrorSerializerSettings)}")
        Catch
        End Try

        Throw New ApplicationException(sbMensagem.ToString, ex)
    End Try

    Return resposta
End Function

异常栈信息 #

错误信息:
Erro ao Autenticar（认证出错）
Handler:
{
  "AuthenticationLevel": 1,
  "ImpersonationLevel": 4,
  "AllowPipelining": true,
  "UnsafeAuthenticatedConnectionSharing": false,
  "MaxResponseHeadersLength": 64,
  "ReadWriteTimeout": 300000,
  "CachePolicy": {
    "Level": 1
  },
  "ContinueTimeout": "00:00:00.3500000",
  "ClientCertificates": [
    {
      "RawData": "RAW_DATA"
    }
  ],
  "ServerCertificateValidationCallback": null,
  "CheckCertificateRevocationList": false,
  "DefaultProxyCredentials": null,
  "MaxConnectionsPerServer": 2147483647,
  "Properties": {},
  "ServerCertificateCustomValidationCallback": null,
  "SslProtocols": 0,
  "SupportsAutomaticDecompression": true,
  "SupportsProxy": true,
  "SupportsRedirectConfiguration": true,
  "UseCookies": true,
  "CookieContainer": {
    "Capacity": 300,
    "Count": 0,
    "MaxCookieSize": 4096,
    "PerDomainCapacity": 20
  },
  "ClientCertificateOptions": 0,
  "AutomaticDecompression": 0,
  "UseProxy": true,
  "Proxy": null,
  "PreAuthenticate": false,
  "UseDefaultCredentials": false,
  "Credentials": null,
  "AllowAutoRedirect": true,
  "MaxAutomaticRedirections": 50,
  "MaxRequestContentBufferSize": 2147483647
}
Client:
{
  "DefaultRequestHeaders": [],
  "BaseAddress": null,
  "Timeout": "00:01:40",
  "MaxResponseContentBufferSize": 2147483647
}
Certificate:
{
  "RawData": "RAW_DATA"
}
Content Data:
grant_type=client_credentials&client_id=CLIENT_ID&client_secret=CLIENT_SECRET
Http Content:
{
  "Headers": [
    {
      "Key": "Content-Type",
      "Value": [
        "application/x-www-form-urlencoded; charset=utf-8"
      ]
    },
    {
      "Key": "Content-Length",
      "Value": [
        "127"
      ]
    }
  ]
}
Resposta:
{
  "Status": 0,
  "Conteudo": null
}
Exception ToString: System.Net.Http.HttpRequestException: 发送请求时出错。 ---> System.Net.WebException: 请求已中止: 无法创建SSL/TLS安全通道。
   at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult, TransportContext& context)
   at System.Net.Http.HttpClientHandler.GetRequestStreamCallback(IAsyncResult ar)
   --- 内部异常堆栈跟踪结束 ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at SIARM.NFSE.Data.ArrecadacaoPIXAPIItau.EnviarAutenticacao()
 (System.ApplicationException)
   at SIARM.NFSE.Data.ArrecadacaoPIXAPIItau.EnviarAutenticacao()
   at SIARM.NFSE.Data.ArrecadacaoPIXAPI.Autenticar()

错误信息:
发送请求时出错。(System.Net.Http.HttpRequestException)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at ArrecadacaoPIXAPIItau.EnviarAutenticacao()

错误信息:
请求已中止: 无法创建SSL/TLS安全通道。(System.Net.WebException)
   at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult, TransportContext& context)
   at System.Net.Http.HttpClientHandler.GetRequestStreamCallback(IAsyncResult ar)

内容的提问来源于stack exchange，提问作者Celso