diff --git a/include/ylt/coro_rpc/impl/coro_connection.hpp b/include/ylt/coro_rpc/impl/coro_connection.hpp
index c98e423e1..f095c1cad 100644
--- a/include/ylt/coro_rpc/impl/coro_connection.hpp
+++ b/include/ylt/coro_rpc/impl/coro_connection.hpp
@@ -514,8 +514,8 @@ class coro_connection : public std::enable_shared_from_this<coro_connection> {
       }
       if (ret.first)
         AS_UNLIKELY {
-          ELOG_ERROR << ret.first.message() << ", "
-                     << "async_write error";
+          ELOG_INFO << ret.first.message() << ", "
+                    << "async_write error";
           close();
           co_return;
         }
diff --git a/include/ylt/standalone/cinatra/coro_http_connection.hpp b/include/ylt/standalone/cinatra/coro_http_connection.hpp
index 35e0feb56..ef42022b7 100644
--- a/include/ylt/standalone/cinatra/coro_http_connection.hpp
+++ b/include/ylt/standalone/cinatra/coro_http_connection.hpp
@@ -433,7 +433,7 @@ class coro_http_connection
     }
 
     if (ec) {
-      CINATRA_LOG_ERROR << "async_write error: " << ec.message();
+      CINATRA_LOG_INFO << "async_write error: " << ec.message();
       close();
       co_return false;
     }
@@ -779,6 +779,8 @@ class coro_http_connection
 
   auto &tcp_socket() { return *socket_wrapper_.socket(); }
 
+  uint64_t conn_id() const { return conn_id_; }
+
   void set_quit_callback(std::function<void(const uint64_t &conn_id)> callback,
                          uint64_t conn_id) {
     quit_cb_ = std::move(callback);
diff --git a/include/ylt/standalone/cinatra/picohttpparser.h b/include/ylt/standalone/cinatra/picohttpparser.h
index 479a8c231..18b2dbb9f 100644
--- a/include/ylt/standalone/cinatra/picohttpparser.h
+++ b/include/ylt/standalone/cinatra/picohttpparser.h
@@ -854,6 +854,12 @@ static const char *parse_headers(const char *buf, const char *buf_end,
           // has_close
           has_close = true;
         }
+        else if (ch == 'k' || ch == 'K') {
+          std::string_view val_str{value, value_len};
+          if (val_str.find("pgrade") != std::string_view::npos) {
+            has_upgrade = true;
+          }
+        }
       }
     }
     headers[*num_headers] = {std::string_view{name, name_len},
diff --git a/src/coro_http/examples/chat_room.cpp b/src/coro_http/examples/chat_room.cpp
index afda21235..11dcaf3a6 100644
--- a/src/coro_http/examples/chat_room.cpp
+++ b/src/coro_http/examples/chat_room.cpp
@@ -37,17 +37,29 @@ struct message_t {
 };
 YLT_REFL(message_t, type, content);
 
-async_simple::coro::Lazy<void> broadcast(auto &conn_map,
-                                         std::string &resp_str) {
-  for (auto &[conn_ptr, user_name] : conn_map) {
-    auto conn = (coro_http_connection *)conn_ptr;
+struct conn_holder {
+  std::weak_ptr<coro_http_connection> conn;
+  std::string user_name;
+};
+
+async_simple::coro::Lazy<std::vector<uint64_t>> broadcast(
+    auto &conn_map, std::string &resp_str) {
+  std::vector<uint64_t> dead_conn_ids;
+  for (auto &[id, holder] : conn_map) {
+    auto conn = holder.conn.lock();
+    if (conn == nullptr) {
+      dead_conn_ids.push_back(id);
+      continue;
+    }
     auto ec = co_await conn->write_websocket(resp_str);
     if (ec) {
       std::cout << ec.message() << "\n";
       continue;
     }
   }
+
   resp_str.clear();
+  co_return dead_conn_ids;
 }
 
 int main() {
@@ -55,21 +67,21 @@ int main() {
   coro_http::coro_http_server server(1, 9001);
   server.set_static_res_dir("", "");
   std::mutex mtx;
-  std::unordered_map<intptr_t, std::string> conn_map;
+  std::unordered_map<uint64_t, conn_holder> conn_map;
   server.set_http_handler<cinatra::GET>(
       "/",
       [&](coro_http_request &req,
           coro_http_response &resp) -> async_simple::coro::Lazy<void> {
         websocket_result result{};
 
-        std::unordered_map<intptr_t, std::string> map;
+        std::unordered_map<uint64_t, conn_holder> map;
         std::string resp_str;
         while (true) {
           result = co_await req.get_conn()->read_websocket();
           if (result.ec) {
             {
               std::scoped_lock lock(mtx);
-              conn_map.erase((intptr_t)req.get_conn());
+              conn_map.erase(req.get_conn()->conn_id());
             }
             break;
           }
@@ -87,7 +99,7 @@ int main() {
             std::string from;
             {
               std::scoped_lock lock(mtx);
-              from = conn_map.at((intptr_t)req.get_conn());
+              from = conn_map.at(req.get_conn()->conn_id()).user_name;
               map = conn_map;
             }
 
@@ -101,11 +113,13 @@ int main() {
               std::scoped_lock lock(mtx);
               if (msg.type == "login") {
                 user_name = std::string{msg.content};
-                conn_map.emplace((intptr_t)req.get_conn(), user_name);
+                conn_map.emplace(
+                    req.get_conn()->conn_id(),
+                    conn_holder{req.get_conn()->shared_from_this(), user_name});
               }
               else {
-                user_name = conn_map.at((intptr_t)req.get_conn());
-                conn_map.erase((intptr_t)req.get_conn());
+                user_name = conn_map.at(req.get_conn()->conn_id()).user_name;
+                conn_map.erase(req.get_conn()->conn_id());
               }
               map = conn_map;
             }
@@ -114,7 +128,7 @@ int main() {
               std::vector<std::string> user_list;
               std::transform(map.begin(), map.end(),
                              std::back_inserter(user_list), [](auto &kv) {
-                               return kv.second;
+                               return kv.second.user_name;
                              });
               logout_info_t info{msg.type, user_name, std::move(user_list)};
               struct_json::to_json(info, resp_str);
@@ -123,7 +137,15 @@ int main() {
 
           std::cout << result.data << "\n";
 
-          co_await broadcast(map, resp_str);
+          auto ids = co_await broadcast(map, resp_str);
+          if (!ids.empty()) {
+            // clean dead connection
+            std::scoped_lock lock(mtx);
+            for (auto id : ids) {
+              conn_map.erase(id);
+            }
+          }
+
           if (msg.type == "logout") {
             break;
           }
diff --git a/src/coro_http/examples/client.html b/src/coro_http/examples/client.html
index d0736ca77..8d2b32ef9 100644
--- a/src/coro_http/examples/client.html
+++ b/src/coro_http/examples/client.html
@@ -3,6 +3,7 @@
 
 <head>
     <title></title>
+    <link rel="icon" href="data:,">
     <meta http-equiv="content-type" content="text/html;charset=utf-8">
     <style>
         p {