MongoDB C# driver timeout

Question

I am trying to post some data into my remote mongodb instance which is a replica set, however I am getting a timeout exception saying that the host is not found? I have also read around and added ?connect=replicaSet at the end of the connection string but this did not help.

Here is my connection string

private MongoClient client = new MongoClient("mongodb://10.250.8.1:27017,10.250.8.2:27017,10.250.8.3:27017?connect=replicaSet");

and here is the exception that has been thrown:

{"A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = WritableServerSelector, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 } }. Client view of cluster state is { ClusterId : \"1\", ConnectionMode : \"ReplicaSet\", Type : \"ReplicaSet\", State : \"Disconnected\", Servers : [{ ServerId: \"{ ClusterId : 1, EndPoint : \"Unspecified/wsmongodb001:27017\" }\", EndPoint: \"Unspecified/wsmongodb001:27017\", State: \"Disconnected\", Type: \"Unknown\", HeartbeatException: \"MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: No such host is known\r\n   at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)\r\n   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<ConnectAsync>d__7.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<CreateStreamAsync>d__4.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n   --- End of inner exception stack trace ---\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Servers.ClusterableServer.<HeartbeatAsync>d__42.MoveNext()\" }, { ServerId: \"{ ClusterId : 1, EndPoint : \"Unspecified/wsmongodb002:27017\" }\", EndPoint: \"Unspecified/wsmongodb002:27017\", State: \"Disconnected\", Type: \"Unknown\", HeartbeatException: \"MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: No such host is known\r\n   at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)\r\n   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<ConnectAsync>d__7.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<CreateStreamAsync>d__4.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n   --- End of inner exception stack trace ---\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Servers.ClusterableServer.<HeartbeatAsync>d__42.MoveNext()\" }, { ServerId: \"{ ClusterId : 1, EndPoint : \"Unspecified/wsmongodb003:27017\" }\", EndPoint: \"Unspecified/wsmongodb003:27017\", State: \"Disconnected\", Type: \"Unknown\", HeartbeatException: \"MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: No such host is known\r\n   at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)\r\n   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<ConnectAsync>d__7.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.TcpStreamFactory.<CreateStreamAsync>d__4.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n   --- End of inner exception stack trace ---\r\n   at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__47.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable.ConfiguredTaskAwaiter.GetResult()\r\n   at MongoDB.Driver.Core.Servers.ClusterableServer.<HeartbeatAsync>d__42.MoveNext()\" }] }."}

Answer 1

Here is the most important part of your error message:

Client view of cluster state is
{  
   ClusterId: "1",
   ConnectionMode: "ReplicaSet",
   Type: "ReplicaSet",
   State: "Disconnected",
   Servers: [{  
      ServerId: {
         ClusterId: 1,
         EndPoint: "Unspecified/wsmongodb001:27017"
      },
      EndPoint: "Unspecified/wsmongodb001:27017",
      State: "Disconnected",
      Type: "Unknown",
      HeartbeatException: "[...] System.Net.Sockets.SocketException: No such host is known [...]"
   }]
}

Note the "No such host is known" part of the field HeartbeatException.

Your replica set is configured with host names instead of IP addresses. Apparently, your client application cannot resolve wsmongodb001 to an IP address.

You will need to:

1. Make sure that your replica set is up and running. Manually connect to one of the servers from the mongo shell, run rs.status() and check that there is a primary and there are no errors.
2. Make sure that all domain names that are configured in your replica set via rs.conf() are accessible to your client app. If you are unsure if they are, just open a command prompt on the machine that runs the app and ping every domain name.