Updated to version 10.2.4

CryptoExchange.Net/Clients/SocketApiClient.cs

@@ -802,7 +802,6 @@ namespace CryptoExchange.Net.Clients
             return new CallResult<HighPerfSocketConnection<TUpdateType>>(socketConnection);
         }
 
-
         /// <summary>
         /// Process an unhandled message
         /// </summary>
@@ -811,6 +810,14 @@ namespace CryptoExchange.Net.Clients
         {
         }
 
+        /// <summary>
+        /// Process an unhandled message
+        /// </summary>
+        /// <param name="connection">The socket connection</param>
+        /// <param name="typeIdentifier">The type as identified</param>
+        /// <param name="data">The data</param>
+        protected internal virtual bool HandleUnhandledMessage(SocketConnection connection, string typeIdentifier, ReadOnlySpan<byte> data) => false;
+
         /// <summary>
         /// Process connect rate limited
         /// </summary>

CryptoExchange.Net/Converters/SystemTextJson/CommaSplitStringConverter.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace CryptoExchange.Net.Converters.SystemTextJson
+{
+    /// <summary>
+    /// Converter for comma separated string values
+    /// </summary>
+    public class CommaSplitStringConverter : JsonConverter<string[]>
+    {
+        /// <inheritdoc />
+        public override string[]? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            var str = reader.GetString();
+            if (string.IsNullOrEmpty(str))
+                return [];
+
+            return str!.Split(',').ToArray() ?? [];
+        }
+
+        /// <inheritdoc />
+        public override void Write(Utf8JsonWriter writer, string[] value, JsonSerializerOptions options)
+        {
+            writer.WriteStringValue(string.Join(",", value));
+        }
+    }
+}

CryptoExchange.Net/CryptoExchange.Net.csproj

@@ -6,9 +6,9 @@
     <PackageId>CryptoExchange.Net</PackageId>
     <Authors>JKorf</Authors>
     <Description>CryptoExchange.Net is a base library which is used to implement different cryptocurrency (exchange) API's. It provides a standardized way of implementing different API's, which results in a very similar experience for users of the API implementations.</Description>
-    <PackageVersion>10.2.2</PackageVersion>
+    <PackageVersion>10.2.4</PackageVersion>
-    <AssemblyVersion>10.2.2</AssemblyVersion>
+    <AssemblyVersion>10.2.4</AssemblyVersion>
-    <FileVersion>10.2.2</FileVersion>
+    <FileVersion>10.2.4</FileVersion>
     <PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
     <PackageTags>OKX;OKX.Net;Mexc;Mexc.Net;Kucoin;Kucoin.Net;Kraken;Kraken.Net;Huobi;Huobi.Net;CoinEx;CoinEx.Net;Bybit;Bybit.Net;Bitget;Bitget.Net;Bitfinex;Bitfinex.Net;Binance;Binance.Net;CryptoCurrency;CryptoCurrency Exchange;CryptoExchange.Net</PackageTags>
     <RepositoryType>git</RepositoryType>

CryptoExchange.Net/ExtensionMethods.cs

@@ -74,8 +74,13 @@ namespace CryptoExchange.Net
                 {
                     if (serializationType == ArrayParametersSerialization.Array)
                     {
-                        foreach(var entry in (object[])parameter.Value)
+                        bool firstArrayValue = true;
+                        foreach (var entry in (object[])parameter.Value)
                         {
+                            if (!firstArrayValue)
+                                uriString.Append('&');
+                            firstArrayValue = false;
+
                             uriString.Append(parameter.Key);
                             uriString.Append("[]=");
                             if (urlEncodeValues)
@@ -611,6 +616,26 @@ namespace CryptoExchange.Net
 
             return services;
         }
+
+        /// <summary>
+        /// Convert a hex encoded string to byte array
+        /// </summary>
+        /// <param name="hexString"></param>
+        /// <returns></returns>
+        public static byte[] HexStringToBytes(this string hexString)
+        {
+            if (hexString.StartsWith("0x"))
+                hexString = hexString.Substring(2);
+
+            byte[] bytes = new byte[hexString.Length / 2];
+            for (int i = 0; i < hexString.Length; i += 2)
+            {
+                string hexSubstring = hexString.Substring(i, 2);
+                bytes[i / 2] = Convert.ToByte(hexSubstring, 16);
+            }
+
+            return bytes;
+        }
     }
 }
 

CryptoExchange.Net/Objects/ParameterCollection.cs

@@ -96,6 +96,23 @@ namespace CryptoExchange.Net.Objects
                 base.Add(key, value.Value.ToString(CultureInfo.InvariantCulture));
         }
 
+        /// <summary>
+        /// Add a DateTime value as string
+        /// </summary>
+        public void AddString(string key, DateTime value)
+        {
+            base.Add(key, value.ToString("yyyy-MM-ddTHH:mm:ssZ"));
+        }
+
+        /// <summary>
+        /// Add a DateTime value as string. Not added if value is null
+        /// </summary>
+        public void AddOptionalString(string key, DateTime? value)
+        {
+            if (value != null)
+                base.Add(key, value.Value.ToString("yyyy-MM-ddTHH:mm:ssZ"));
+        }
+
         /// <summary>
         /// Add a datetime value as milliseconds timestamp
         /// </summary>
@@ -241,6 +258,45 @@ namespace CryptoExchange.Net.Objects
                 base.Add(key, int.Parse(stringVal));
             }
         }
+        
+        /// <summary>
+        /// Add key as comma separated values
+        /// </summary>
+        public void AddCommaSeparated(string key, IEnumerable<string> values)
+        {
+            base.Add(key, string.Join(",", values));
+        }
+
+        /// <summary>
+        /// Add key as comma separated values if there are values provided
+        /// </summary>
+        public void AddOptionalCommaSeparated(string key, IEnumerable<string>? values)
+        {
+            if (values == null || !values.Any())
+                return;
+
+            base.Add(key, string.Join(",", values));
+        }
+
+        /// <summary>
+        /// Add key as boolean lower case value
+        /// </summary>
+        public void AddBoolString(string key, bool value)
+        {
+            base.Add(key, value.ToString().ToLower());
+        }
+
+        /// <summary>
+        /// Add key as boolean lower case value if it's not null
+        /// </summary>
+        public void AddOptionalBoolString(string key, bool? value)
+        {
+            if (value == null)
+                return;
+
+            base.Add(key, value.ToString()!.ToLower());
+        }
+
 
         /// <summary>
         /// Set the request body. Can be used to specify a simple value or array as the body instead of an object

CryptoExchange.Net/OrderBook/SymbolOrderBook.cs

@@ -640,6 +640,34 @@ namespace CryptoExchange.Net.OrderBook
             return new CallResult<bool>(true);
         }
 
+        /// <summary>
+        /// Wait until an update has been buffered
+        /// </summary>
+        /// <param name="timeout">Max wait time</param>
+        /// <param name="ct">Cancellation token</param>
+        /// <returns></returns>
+        protected async Task<CallResult<bool>> WaitUntilFirstUpdateBufferedAsync(TimeSpan timeout, CancellationToken ct)
+        {
+            var startWait = DateTime.UtcNow;
+            while (_processBuffer.Count == 0)
+            {
+                if (ct.IsCancellationRequested)
+                    return new CallResult<bool>(new CancellationRequestedError());
+
+                if (DateTime.UtcNow - startWait > timeout)
+                    return new CallResult<bool>(new ServerError(new ErrorInfo(ErrorType.OrderBookTimeout, "Timeout while waiting for data")));
+
+                try
+                {
+                    await Task.Delay(20, ct).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException)
+                { }
+            }
+
+            return new CallResult<bool>(true);
+        }
+
         /// <summary>
         /// IDisposable implementation for the order book
         /// </summary>
@@ -1002,7 +1030,8 @@ namespace CryptoExchange.Net.OrderBook
 
         private SequenceNumberResult ValidateLiveSequenceNumber(long sequenceNumber)
         {
-            if (sequenceNumber < LastSequenceNumber)
+            if (sequenceNumber < LastSequenceNumber 
+                && (_firstUpdateAfterSnapshotDone || !_skipSequenceCheckFirstUpdateAfterSnapshotSet))
                 // Update is somehow from before the current state
                 return SequenceNumberResult.OutOfSync;
 

CryptoExchange.Net/Sockets/Default/SocketConnection.cs

@@ -571,8 +571,12 @@ namespace CryptoExchange.Net.Sockets.Default
 
             if (deserializationType == null)
             {
-                // No handler found for identifier either, can't process
+                if (!ApiClient.HandleUnhandledMessage(this, typeIdentifier, data))
-                _logger.LogWarning("Failed to determine message type for identifier {Identifier}. Data: {Message}", typeIdentifier, Encoding.UTF8.GetString(data.ToArray()));
+                {
+                    // No handler found for identifier either, can't process
+                    _logger.LogWarning("Failed to determine message type for identifier {Identifier}. Data: {Message}", typeIdentifier, Encoding.UTF8.GetString(data.ToArray()));
+                }
+                    
                 return;
             }
             

CryptoExchange.Net/TimeOffsetManager.cs

@@ -113,7 +113,8 @@ namespace CryptoExchange.Net
         /// <param name="api"></param>
         internal static void RegisterRestApi(string api)
         {
-            _lastRestDelays[api] = new RestTimeOffset();
+            if (!_lastRestDelays.ContainsKey(api))
+                _lastRestDelays.TryAdd(api, new RestTimeOffset());
         }
 
         /// <summary>

README.md

@@ -66,6 +66,16 @@ Make a one time donation in a crypto currency of your choice. If you prefer to d
 Alternatively, sponsor me on Github using [Github Sponsors](https://github.com/sponsors/JKorf). 
 
 ## Release notes
+* Version 10.2.4 - 17 Jan 2026
+    * Added WaitUntilFirstUpdateBufferedAsync method on SymbolOrderBook
+    * Added some util methods
+    * Added CommaSplitStringConverter
+    * Fixed sequence validation bug SymbolOrderBook
+
+* Version 10.2.3 - 14 Jan 2026
+    * Added HandleUnhandledMessage virtual method to SocketApiClient to allow some processing for messages which couldn't be mapped via the normal way
+    * Fixed semaphore exception when creating a new REST client while time sync is in progress on another client
+
 * Version 10.2.2 - 13 Jan 2026
     * Allow the same websocket connection sequence number to be recorded multiple times