using System;using MongoDB.Bson;using MongoDB.Driver;
namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            MongoClient dbClient = new MongoClient("mongodb://127.0.0.1:27017/");
            var database = dbClient.GetDatabase("sample_training");
            var collection = database.GetCollection<BsonDocument>("grades");
            var document = new BsonDocument
            {
                { "student_id", 1 },
                { "scores", new BsonArray
                    {
                    new BsonDocument{ {"type", "exam"}, {"score", 88.12334193287023 } },
                    new BsonDocument\{ {"type", "quiz"}, {"score", 74.92381029342834 } },
                    new BsonDocument\{ {"type", "homework"}, {"score", 89.97929384290324 } },
                    new BsonDocument\{ {"type", "homework"}, {"score", 82.12931030513218 } }
                    }
                },
                { "class_id", 480}
            };           
           collection.InsertOne(document);      
       }
    }
}

Unhandled Exception:
System.TimeoutException: A timeout occurred after 30000ms selecting a server using CompositeServerSelector{ Selectors = MongoDB.Driver.MongoClient+AreSessionsSupportedServerSelector, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 }, OperationsCountServerSelector }. Client view of cluster state is { ClusterId : "1", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 1, EndPoint : "127.0.0.1:27017" }", EndPoint: "127.0.0.1:27017", ReasonChanged: "Heartbeat", State: "Disconnected", ServerVersion: , TopologyVersion: , Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server.
 ---> MongoDB.Driver.MongoConnectionException: An exception occurred while receiving a message from the server.
 ---> System.FormatException: The size of the message is invalid.
   at MongoDB.Driver.Core.Connections.BinaryConnection.EnsureMessageSizeIsValid(Int32 messageSize)
   at MongoDB.Driver.Core.Connections.BinaryConnection.ReceiveBuffer(CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at MongoDB.Driver.Core.Connections.BinaryConnection.ReceiveBuffer(CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.BinaryConnection.ReceiveBuffer(Int32 responseTo, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at MongoDB.Driver.Core.Connections.BinaryConnection.Dropbox.RemoveMessage(Int32 responseTo)
   at MongoDB.Driver.Core.Connections.BinaryConnection.ReceiveBuffer(Int32 responseTo, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.BinaryConnection.ReceiveMessage(Int32 responseTo, IMessageEncoderSelector encoderSelector, MessageEncoderSettings messageEncoderSettings, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.WireProtocol.CommandUsingQueryMessageWireProtocol`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].Execute(IConnection connection, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.WireProtocol.CommandWireProtocol`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].Execute(IConnection connection, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.HelloHelper.GetResult(IConnection connection, CommandWireProtocol`1 helloProtocol, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.ConnectionInitializer.SendHello(IConnection connection, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.BinaryConnection.OpenHelper(CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at MongoDB.Driver.Core.Connections.BinaryConnection.OpenHelper(CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Connections.BinaryConnection.Open(CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Servers.ServerMonitor.InitializeConnection(CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Servers.ServerMonitor.Heartbeat(CancellationToken cancellationToken)", LastHeartbeatTimestamp: "2023-06-12T14:03:57.6330997Z", LastUpdateTimestamp: "2023-06-12T14:03:57.6331002Z" }] }.
   at MongoDB.Driver.Core.Clusters.Cluster.ThrowTimeoutException(IServerSelector selector, ClusterDescription description)
   at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChangedHelper.HandleCompletedTask(Task completedTask)
   at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChanged(IServerSelector selector, ClusterDescription description, Task descriptionChangedTask, TimeSpan timeout, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Clusters.Cluster.SelectServer(IServerSelector selector, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoClient.AreSessionsSupportedAfterServerSelection(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoClient.AreSessionsSupported(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoClient.StartImplicitSession(CancellationToken cancellationToken)
   at MongoDB.Driver.OperationExecutor.StartImplicitSession(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].UsingImplicitSession[BulkWriteResult`1](Func`2 func, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].BulkWrite(IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionBase`1.<>c__DisplayClass68_0[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].<InsertOne>b__0(IEnumerable`1 requests, BulkWriteOptions bulkWriteOptions)
   at MongoDB.Driver.MongoCollectionBase`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].InsertOne(BsonDocument document, InsertOneOptions options, Action`2 bulkWrite)
   at MongoDB.Driver.MongoCollectionBase`1[[MongoDB.Bson.BsonDocument, MongoDB.Bson, Version=2.19.2.0, Culture=neutral, PublicKeyToken=null]].InsertOne(BsonDocument document, InsertOneOptions options, CancellationToken cancellationToken)
   at MongoDBCRUDExample.Program.Main(String[] args)