Marketing cloud SOAP API Retrieve request timeout exception

Question

I am trying to download the subscribers from marketing cloud using the SOAP API and it throws the following exception after couple of iterations.

It does not fail consistently. Sometimes it completes 50 iterations and fails and sometimes it fails after 5 or 10 iterations.

Here is the code I am using to make the retrieve request:

public List<Subscriber> GetSubscribers(string RequestId = null)
    {
        string message = string.Empty;
        _lstSubscribers = new List<Subscriber>();
        SoapClient client = new SoapClient();
        client.ClientCredentials.UserName.UserName = _username;
        client.ClientCredentials.UserName.Password = _password;

        RetrieveRequest retrieveRequest = new RetrieveRequest();
        retrieveRequest.ObjectType = "Subscriber";

        string[] props = { "Client.ID", "CreatedDate", "EmailAddress", "EmailTypePreference", "ID", "PartnerKey", "SubscriberKey", "UnsubscribedDate" };
        retrieveRequest.Properties = props;

        retrieveRequest.ClientIDs = new ClientID[] { _clientID };
        //retrieveRequest.QueryAllAccounts = true;
        //retrieveRequest.QueryAllAccountsSpecified = true;

        String requestId = RequestId; 
        String response = string.Empty;
        int tryCount = 0;
        try
        {
            RunRetrieveRequest(client, out requestId, out response, retrieveRequest);
        }
        catch (Exception ex)
        {
            if (response == "MoreDataAvailable")
            {
                tryCount++;
                if (tryCount <= 10)
                {

                }

                retrieveRequest.ContinueRequest = requestId;
                RunRetrieveRequest(client, out requestId, out response, retrieveRequest);
            }
        }
        return _lstSubscribers;
    }

    private void RunRetrieveRequest(SoapClient client, out string RequestID, out string Response, RetrieveRequest Request)
    {
        List<Subscriber> lstSubscribers = new List<Subscriber>();
        APIObject[] results = null;
        do
        {
            Response = client.Retrieve(Request, out RequestID, out results);

            Subscriber subscriber = null;
            if (Response != null && results != null)
            {
                foreach (var result in results)
                {
                    subscriber = (Subscriber)result;
                    _lstSubscribers.Add(subscriber);
                }
            }
            Request = new RetrieveRequest();
            Request.ContinueRequest = RequestID;
        } while (Response == "MoreDataAvailable");
    }

Here is the config. I have tried changing the timeout attributes from 30 to 59, but this didn't help.

<system.serviceModel>
    <bindings>
        <basicHttpBinding>
            <binding name="SoapBinding">
                <security mode="Transport" />
            </binding>
            <binding name="SoapBinding1" />
        </basicHttpBinding>
      <customBinding>
        <binding name="SoapBinding" closeTimeout="00:59:00" openTimeout="00:59:00" receiveTimeout="00:59:00" sendTimeout="00:59:00">
          <security authenticationMode="UserNameOverTransport">
            <secureConversationBootstrap />
          </security>
          <textMessageEncoding messageVersion="Soap11WSAddressingAugust2004" />
          <httpsTransport maxReceivedMessageSize="655360000" />
        </binding>
      </customBinding>
    </bindings>
    <client>
        <endpoint address="https://mySubDomain.soap.marketingcloudapis.com/Service.asmx"
            binding="customBinding" bindingConfiguration="SoapBinding"
            contract="sfmc.Soap" name="Soap" />
    </client>
</system.serviceModel>

I will appreciate any help or suggestion. Thanks in advance.

Answer 1

I have been able to resolve this issue and posting the answer as it may help someone else struggling with a similar issue. The Salesforce marketing cloud API (both SOAP and REST) has stopped supporting the default TLS 1.0 protocol. So I needed to add the following code before I sent any request to the API.

System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12 | System.Net.SecurityProtocolType.Tls11 | System.Net.SecurityProtocolType.Tls;

The following link has more explained insights on the same.

WCF Error "This could be due to the fact that the server certificate is not configured properly with HTTP.SYS in the HTTPS case"