diff --git a/src/AutoConnectDefs.h b/src/AutoConnectDefs.h
index a29ac80..667619f 100644
--- a/src/AutoConnectDefs.h
+++ b/src/AutoConnectDefs.h
@@ -205,13 +205,16 @@
 // The purpose of this macro is to avoid the use of invalid member
 // functions due to differences in the version of the library which
 // AutoConnect depends on.
-#define AC_HAS_FUNC(func) \
-template<typename T> \
-struct has_func_##func { \
-  static auto check(...) -> decltype(std::false_type()); \
-  template<typename U> \
-  static auto check(U&) -> decltype(static_cast<decltype(U::func)*>(&U::func), std::true_type()); \
-  enum : bool { value = decltype(check(std::declval<T&>()))::value }; \
+#define AC_HAS_FUNC(func)                                 \
+template<typename T>                                      \
+struct has_func_##func {                                  \
+ private:                                                 \
+  typedef char  one;                                      \
+  typedef long  two;                                      \
+  template<typename U> static one test(typeof(&U::func)); \
+  template<typename U> static two test(...);              \
+ public:                                                  \
+  enum { value = sizeof(test<T>(0)) == sizeof(char) };    \
 }
 
 #endif // _AUTOCONNECTDEFS_H_
diff --git a/src/AutoConnectUpdate.cpp b/src/AutoConnectUpdate.cpp
index 3d1bdea..8c783ca 100644
--- a/src/AutoConnectUpdate.cpp
+++ b/src/AutoConnectUpdate.cpp
@@ -85,17 +85,16 @@ namespace AutoConnectUtil {
 AC_HAS_FUNC(onProgress);
 
 template<typename T>
-typename std::enable_if<AutoConnectUtil::has_func_onProgress<T>::value, AutoConnectUpdate::AC_UPDATEDIALOG_t>::type onProgress(const T& updater, std::function<void(size_t, size_t)> fn) {
+typename std::enable_if<AutoConnectUtil::has_func_onProgress<T>::value, AutoConnectUpdate::AC_UPDATEDIALOG_t>::type onProgress(T& updater, std::function<void(size_t, size_t)> fn) {
   updater.onProgress(fn);
-  AC_DBG("Callback enabled\n");
+  AC_DBG("An updater keeps callback\n");
   return AutoConnectUpdate::UPDATEDIALOG_METER;
 }
 
 template<typename T>
-typename std::enable_if<!AutoConnectUtil::has_func_onProgress<T>::value, AutoConnectUpdate::AC_UPDATEDIALOG_t>::type onProgress(const T& updater, std::function<void(size_t, size_t)> fn) {
+typename std::enable_if<!AutoConnectUtil::has_func_onProgress<T>::value, AutoConnectUpdate::AC_UPDATEDIALOG_t>::type onProgress(T& updater, std::function<void(size_t, size_t)> fn) {
   (void)(updater);
   (void)(fn);
-  AC_DBG("Callback disabled\n");
   return AutoConnectUpdate::UPDATEDIALOG_LOADER;
 }
 }
@@ -143,11 +142,6 @@ void AutoConnectUpdate::attach(AutoConnect& portal) {
 
   _status = UPDATE_IDLE;
 
-  // Register the callback to inform the update progress 
-  _dialog = AutoConnectUtil::onProgress<UpdateVariedClass>(Update, std::bind(&AutoConnectUpdate::_inProgress, this, std::placeholders::_1, std::placeholders::_2));
-  // Update.onProgress(std::bind(&AutoConnectUpdate::_inProgress, this, std::placeholders::_1, std::placeholders::_2));
-  // _dialog = UPDATEDIALOG_METER;
-
   // Adjust the client dialog pattern according to the callback validity
   // of the UpdateClass.
   AutoConnectElement* loader = _progress->getElement(String(F("loader")));
@@ -172,6 +166,9 @@ void AutoConnectUpdate::attach(AutoConnect& portal) {
   AC_DBG("AutoConnectUpdate attached\n");
   if (WiFi.status() == WL_CONNECTED)
     enable();
+
+  // Register the callback to inform the update progress
+  _dialog = AutoConnectUtil::onProgress<UpdateVariedClass>(Update, std::bind(&AutoConnectUpdate::_inProgress, this, std::placeholders::_1, std::placeholders::_2));
 }
 
 /**
@@ -217,17 +214,16 @@ void AutoConnectUpdate::handleUpdate(void) {
       // execute it accordingly. It is only this process point that
       // requests update processing.
       if (_status == UPDATE_START) {
-        _ws->loop();  // Crawl the connection request.
         unsigned long tm = millis();
-        while (_ws->connectedClients() <= 0) {
-          if (millis() - tm > AUTOCONNECT_UPDATE_TIMEOUT) {
+        while (!_wsConnected) {
+          if (millis() - tm > 30 * 1000) {
             AC_DBG("WebSocket client connection timeout, update ignored\n");
             break;
           }
           _ws->loop();  // Crawl the connection request.
         }
         // Launch the update
-        if (_ws->connectedClients())
+        if (_wsConnected)
           update();
         else
           _status = UPDATE_IDLE;
@@ -276,7 +272,7 @@ AC_UPDATESTATUS_t AutoConnectUpdate::update(void) {
     }
     _WiFiClient.reset(nullptr);
     // Request the client to close the WebSocket.
-    _ws->sendTXT(_wsClient, "#e", 2);
+    _ws->sendTXT(_wsClient, "#e");
   }
   else {
     AC_DBG("An update has not specified");
@@ -454,6 +450,7 @@ String AutoConnectUpdate::_onUpdate(AutoConnectAux& progress, PageArgument& args
   AutoConnectElement* wsurl = progress.getElement(String(F("wsurl")));
   wsurl->value = "ws://" + WiFi.localIP().toString() + ':' + AUTOCONNECT_WEBSOCKETPORT;
   AC_DBG("Cast WS %s\n", wsurl->value.c_str());
+  _wsConnected = false;
   _status = UPDATE_START;
   return String("");
 }
@@ -473,6 +470,8 @@ String AutoConnectUpdate::_onResult(AutoConnectAux& result, PageArgument& args)
 
   if (_ws) {
     _ws->close();
+    while (_wsConnected)
+      _ws->loop();
     _ws.reset(nullptr);
   }
 
@@ -512,6 +511,10 @@ void AutoConnectUpdate::_inProgress(size_t amount, size_t size) {
 
 void AutoConnectUpdate::_wsEvent(uint8_t client, WStype_t event, uint8_t* payload, size_t length) {
   AC_DBG("WS client:%d event(%d)\n", client, event);
-  if (event == WStype_CONNECTED)
+  if (event == WStype_CONNECTED) {
+    _wsConnected = true;
     _wsClient = client;
+  }
+  else if (event == WStype_DISCONNECTED)
+    _wsConnected = false;
 }
diff --git a/src/AutoConnectUpdate.h b/src/AutoConnectUpdate.h
index 879d908..679dc1d 100644
--- a/src/AutoConnectUpdate.h
+++ b/src/AutoConnectUpdate.h
@@ -131,6 +131,7 @@ class AutoConnectUpdate : public HTTPUpdateClass {
 
   std::unique_ptr<WebSocketsServer> _ws;      /**< Reports the update progress measure */
   uint8_t _wsClient;                          /**< WebSocket client id */
+  bool    _wsConnected;                       /**< WebSocket connection status */
   size_t  _amount;                            /**< Received amound bytes */
   size_t  _binSize;                           /**< Updater binary size */
 
diff --git a/src/AutoConnectUpdatePage.h b/src/AutoConnectUpdatePage.h
index 663f578..d6f5c6d 100644
--- a/src/AutoConnectUpdatePage.h
+++ b/src/AutoConnectUpdatePage.h
@@ -25,7 +25,7 @@ const AutoConnectUpdate::ACPage_t AutoConnectUpdate::_auxCatalog PROGMEM = {
 // Define the AUTOCONNECT_URI_UPDATE_ACT page to display during the
 // update process.
 const AutoConnectUpdate::ACElementProp_t AutoConnectUpdate::_elmProgress[] PROGMEM = {
-  { AC_Element, "loader", "<style>.loader{border:2px solid #f3f3f3;border-radius:50%;border-top:2px solid #555;width: 12px;height:12px;-webkit-animation:spin 1s linear infinite;animation:spin 1s linear infinite}@-webkit-keyframes spin{0%{-webkit-transform:rotate(0deg)}100%{-webkit-transform:rotate(360deg)}}@keyframes spin{0%{transform:rotate(0deg)}100%{transform:rotate(360deg)}}</style>", nullptr },
+  { AC_Element, "loader", "<style>.loader{border:2px solid #f3f3f3;border-radius:50%;border-top:2px solid #555;width:12px;height:12px;-webkit-animation:spin 1s linear infinite;animation:spin 1s linear infinite}@-webkit-keyframes spin{0%{-webkit-transform:rotate(0)}100%{-webkit-transform:rotate(360deg)}}@keyframes spin{0%{transform:rotate(0)}100%{transform:rotate(360deg)}}</style>", nullptr },
   { AC_Element, "c1", "<div style=\"display:inline-block\">", nullptr },
   { AC_Element, "binname", nullptr, nullptr },
   { AC_Element, "c2", "&ensp;from&ensp;", nullptr },
@@ -35,10 +35,10 @@ const AutoConnectUpdate::ACElementProp_t AutoConnectUpdate::_elmProgress[] PROGM
   { AC_Element, "progress_loader", "<div class=\"loader\" />", nullptr },
   { AC_Element, "c4", "</span></div></div>", nullptr },
   { AC_Text, "status", nullptr, nullptr },
-  { AC_Element, "c5", "<script type=\"text/javascript\">var ws;window.onload=function(){ws=new WebSocket('", nullptr },
+  { AC_Element, "c5", "<script type=\"text/javascript\">var ws;window.onload=function(){(ws=new WebSocket(\"", nullptr },
   { AC_Element, "wsurl", nullptr, nullptr },
-  { AC_Element, "c6", "');ws.onopen=function(){ws.onmessage=function(e){var pl=e.data.split(',');if(pl[0]=='#e'){location.href='/_ac/update_result';}else if(pl[0]=='#p'){incr(pl[1]);}};};ws.onclose=function(e){console.log('WS close('+e.code+')'+e.reason);if(e.code!=1000){document.getElementById('status').textContent='WebSocket connection closed. ('+e.code+')';}};ws.onerror=function(e){if(ws.readyState==1){document.getElementById('status').textContent='WebSocket '+e.type;}};};window.onbeforeunload=function(){ws.close();};", nullptr },
-  { AC_Element, "inprogress_meter", "function incr(pv){var iv=pv.split(':');var pb=document.getElementById('progress').getElementsByTagName('meter');pb[0].setAttribute('value',iv[0]);pb[0].setAttribute('max',iv[1]);}", nullptr },
+  { AC_Element, "c6", "\")).onopen=function(){ws.onmessage=function(e){var o=e.data.split(\",\");\"#e\"==o[0]?ws.close(1e3):\"#p\"==o[0]&&incr(o[1])}},ws.onclose=function(e){console.log(\"WS close(\"+e.code+\") \"+e.reason),1e3!=e.code&&(document.getElementById(\"status\").textContent=\"WebSocket connection closed. (\"+e.code+\")\"),location.href=\"" AUTOCONNECT_URI_UPDATE_RESULT "\"},ws.onerror=function(e){1==ws.readyState&&(document.getElementById(\"status\").textContent=\"WebSocket \"+e.type)}},window.onbeforeunload=function(){ws.close()};", nullptr },
+  { AC_Element, "inprogress_meter", "function incr(e){var t=e.split(\":\"),r=document.getElementById(\"progress\").getElementsByTagName(\"meter\");r[0].setAttribute(\"value\",t[0]),r[0].setAttribute(\"max\",t[1])}", nullptr },
   { AC_Element, "inprogress_loader", "function incr(pv){}", nullptr },
   { AC_Element, "c7", "</script>", nullptr },
 };
diff --git a/src/AutoConnectUploadImpl.h b/src/AutoConnectUploadImpl.h
index 2073e61..553bbc6 100644
--- a/src/AutoConnectUploadImpl.h
+++ b/src/AutoConnectUploadImpl.h
@@ -43,12 +43,12 @@ namespace AutoConnectUtil {
 AC_HAS_FUNC(end);
 
 template<typename T>
-typename std::enable_if<AutoConnectUtil::has_func_end<T>::value, void>::type end(const T* media) {
+typename std::enable_if<AutoConnectUtil::has_func_end<T>::value, void>::type end(T* media) {
   media->end();
 }
 
 template<typename T>
-typename std::enable_if<!AutoConnectUtil::has_func_end<T>::value, void>::type end(const T* media) {
+typename std::enable_if<!AutoConnectUtil::has_func_end<T>::value, void>::type end(T* media) {
   (void)(media);
 }
 }