diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b9502f7..b7cbbce9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+yasio-4.3.1
+
+  1. Refining the resource cleanup process for io_service during the handle_stop phase, particularly when a worker thread is terminated externally
+
+  
 yasio-4.3.0
 
   1. Use dynamic buffer for recv
diff --git a/yasio.pc b/yasio.pc
index 8a3900f0..002b7be7 100644
--- a/yasio.pc
+++ b/yasio.pc
@@ -5,6 +5,6 @@ includedir=${exec_prefix}/include
 
 Name: yasio
 Description:  A multi-platform support c++11 library with focus on asio (asynchronous socket I/O) for any client application. 
-Version: 4.3.0
+Version: 4.3.1
 Libs: -L${libdir} 
 Cflags: -I${includedir}/yasio
diff --git a/yasio/config.hpp b/yasio/config.hpp
index f7ac4d29..c41511f5 100644
--- a/yasio/config.hpp
+++ b/yasio/config.hpp
@@ -205,7 +205,7 @@ SOFTWARE.
 /*
 **  The yasio version macros
 */
-#define YASIO_VERSION_NUM 0x040300
+#define YASIO_VERSION_NUM 0x040301
 
 /*
 ** The macros used by io_service.
diff --git a/yasio/io_service.cpp b/yasio/io_service.cpp
index 89e70765..18069957 100644
--- a/yasio/io_service.cpp
+++ b/yasio/io_service.cpp
@@ -376,7 +376,10 @@ int io_transport::write(io_send_buffer&& buffer, completion_cb_t&& handler)
   get_service().wakeup();
   return n;
 }
-int io_transport::do_read(int revent, int& error, highp_time_t&) { return this->call_read(buffer_.data() + offset_, static_cast<int>(buffer_.size() - offset_), revent, error); }
+int io_transport::do_read(int revent, int& error, highp_time_t&)
+{
+  return this->call_read(buffer_.data() + offset_, static_cast<int>(buffer_.size() - offset_), revent, error);
+}
 bool io_transport::do_write(highp_time_t& wait_duration)
 {
   bool ret = false;
@@ -828,6 +831,12 @@ void io_service::handle_stop()
       return;
     }
     this->worker_.join();
+    if (this->state_ != state::AT_EXITING)
+    {
+      // after join if state not AT_EXITING, means worker thread was terminate outside
+      // i.g .net managed exception occurred when invoke c# delegate
+      this->state_ = state::AT_EXITING;
+    }
   }
 
   if (this->state_ != state::AT_EXITING)