diff --git a/net/adc_device_netserver.h b/net/adc_device_netserver.h
index f23373e..737cc57 100644
--- a/net/adc_device_netserver.h
+++ b/net/adc_device_netserver.h
@@ -237,7 +237,7 @@ public:
             auto self(this->shared_from_this());
 
             _netService.asyncReceive(
-                [self, this](std::error_code ec, message_t msg) {
+                [self, this](netservice_t::async_callback_err_t ec, message_t msg) {
                     if (ec) {
                         stop();
                     } else {
@@ -249,7 +249,7 @@ public:
 
                         _netService.asyncSend(
                             *msg_sptr,
-                            [self, msg_sptr, this](std::error_code ec) {
+                            [self, msg_sptr, this](netservice_t::async_callback_err_t ec) {
                                 if (ec) {
                                     stop();
                                 } else {
diff --git a/net/adc_net_concepts.h b/net/adc_net_concepts.h
index 8fbd3e3..e42721b 100644
--- a/net/adc_net_concepts.h
+++ b/net/adc_net_concepts.h
@@ -47,7 +47,7 @@ using adc_common_duration_t = adc_duration_common_type_t<std::chrono::nanosecond
                                                          std::chrono::months,
                                                          std::chrono::years>;
 
-// concepts for asynchronous opereration callback callable first argument type (asynchronous operation error)
+// concepts for asynchronous operation callback callable first argument type (asynchronous operation error)
 //      1) the type must be convertible to boolean and
 //         a) true - asynchronous operation completed without errors
 //         b) false - an error occured
@@ -106,6 +106,9 @@ concept adc_netservice_c = requires(SRVT srv, const SRVT srv_const) {
     typename SRVT::endpoint_t;  // a type representing endpoint of the network service
                                 // underlying protocol
 
+    // asynchronous operation error
+    requires adc_async_callback_err_t<typename SRVT::async_callback_err_t>;
+
     // callback callables for asynchronous operations
     requires adc_async_callback_t<typename SRVT::async_connect_callback_t>;
     requires adc_async_callback_t<typename SRVT::async_send_callback_t>;
diff --git a/net/adc_netserver.h b/net/adc_netserver.h
index c8cf56f..ada6daa 100644
--- a/net/adc_netserver.h
+++ b/net/adc_netserver.h
@@ -9,7 +9,6 @@ ABSTRACT DEVICE COMPONENTS LIBRARY
 #include <filesystem>
 #include <functional>
 #include <list>
-#include <map>
 #include <set>
 #include <unordered_map>
 
diff --git a/net/asio/adc_netservice_asio.h b/net/asio/adc_netservice_asio.h
index b908ac3..25bc0ea 100644
--- a/net/asio/adc_netservice_asio.h
+++ b/net/asio/adc_netservice_asio.h
@@ -134,6 +134,8 @@ public:
     using endpoint_t = typename TRANSPORT_PROTOT::endpoint;
 
     // typedefs for completion tokens (callbacks, required by 'adc_netservice_c' concept)
+    typedef std::error_code async_callback_err_t;
+
     typedef std::function<void(std::error_code)> async_connect_callback_t;
     typedef std::function<void(std::error_code)> async_send_callback_t;
     typedef std::function<void(std::error_code, RMSGT)> async_receive_callback_t;