diff --git a/CHANGELOG.md b/CHANGELOG.md
index db049ec..b3e9f79 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 4.21.9 (Oct 21, 2024)
+
+
+## Improvements
+- Improved logic to prevent crashes in `SessionWebSocketEngine`
+
 ## 4.21.8 (Oct 08, 2024)
 
 
diff --git a/Package.swift b/Package.swift
index 19b5aec..bbae241 100644
--- a/Package.swift
+++ b/Package.swift
@@ -15,8 +15,8 @@ let package = Package(
     targets: [
         .binaryTarget(
             name: "SendbirdChatSDK",
-            url: "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.8/SendbirdChatSDK.xcframework.zip",
-            checksum: "0a71cb5d7f22ec812040a3c1e6c92468a0e02aa900fa0293eeacd8d59dedba60"
+            url: "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.9/SendbirdChatSDK.xcframework.zip",
+            checksum: "fb77128f9f11fb57d5ef23cb83137e4e73faa19815291ad6cd8c566a77b6b794"
         ),
     ]
 )
diff --git a/SendbirdChatSDK.podspec b/SendbirdChatSDK.podspec
index d8886f4..eaa196c 100644
--- a/SendbirdChatSDK.podspec
+++ b/SendbirdChatSDK.podspec
@@ -1,7 +1,7 @@
 
 Pod::Spec.new do |s|
   s.name         = 'SendbirdChatSDK'
-  s.version      = "4.21.8"
+  s.version      = "4.21.9"
   s.summary      = 'Sendbird Chat iOS Framework'
   s.description  = 'Messaging and Chat API for Mobile Apps and Websites'
   s.homepage     = 'https://sendbird.com'
@@ -16,7 +16,7 @@ Pod::Spec.new do |s|
     'Young Hwang' => 'young.hwang@sendbird.com',
     'Kai Lee' => 'kai.lee@sendbird.com'
   }
-  s.source       = { :http => "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.8/SendbirdChatSDK.zip", :sha1 => "c8b91ad5dbdf3e3e647cf75058152cb01bf2fb0e" }
+  s.source       = { :http => "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.9/SendbirdChatSDK.zip", :sha1 => "dfe348e77ccf086d840a1b95a5b9601d06b8c079" }
   s.requires_arc = true
   s.platform = :ios, '12.0'
   s.documentation_url = 'https://sendbird.com/docs/chat'