diff --git a/src/main/java/io/vertx/core/http/impl/Http1xClientConnection.java b/src/main/java/io/vertx/core/http/impl/Http1xClientConnection.java
index b135fdeb1..e820ef001 100644
--- a/src/main/java/io/vertx/core/http/impl/Http1xClientConnection.java
+++ b/src/main/java/io/vertx/core/http/impl/Http1xClientConnection.java
@@ -67,6 +67,10 @@ class Http1xClientConnection extends Http1xConnectionBase<WebSocketImpl> impleme
 
   private static final Logger log = LoggerFactory.getLogger(Http1xClientConnection.class);
 
+  private static final Handler<Object> INVALID_MSG_HANDLER = msg -> {
+    throw new IllegalStateException("Invalid object " + msg);
+  };
+
   private final ConnectionListener<HttpClientConnection> listener;
   private final HttpClientImpl client;
   private final HttpClientOptions options;
@@ -78,7 +82,8 @@ class Http1xClientConnection extends Http1xConnectionBase<WebSocketImpl> impleme
 
   private StreamImpl head;
   private StreamImpl requestInProgress;
-  
+
+  private Handler<Object> invalidMessageHandler = INVALID_MSG_HANDLER;
   private boolean close;
   private Promise<NetSocket> netSocketPromise;
   private int keepAliveTimeout;
@@ -509,7 +514,7 @@ class Http1xClientConnection extends Http1xConnectionBase<WebSocketImpl> impleme
     } else if (msg instanceof WebSocketFrame) {
       handleWsFrame((WebSocketFrame) msg);
     } else {
-      throw new IllegalStateException("Invalid object " + msg);
+      invalidMessageHandler.handle(msg);
     }
   }
 
@@ -568,6 +573,11 @@ class Http1xClientConnection extends Http1xConnectionBase<WebSocketImpl> impleme
           if (inflater != null) {
             pipeline.remove(inflater);
           }
+
+          // removing this codec might fire pending buffers in the HTTP decoder
+          // this happens when the channel reads the HTTP response and the following data in a single buffer
+          Deque<Object> pending = new ArrayDeque<>();
+          invalidMessageHandler = pending::add;
           pipeline.remove("codec");
 
           // replace the old handler with one that handle plain sockets
@@ -583,11 +593,13 @@ class Http1xClientConnection extends Http1xConnectionBase<WebSocketImpl> impleme
           socket.metric(metric());
           pipeline.replace("handler", "handler", VertxHandler.create(socket));
 
-          // removing this codec might fire pending buffers in the HTTP decoder
-          // this happens when the channel reads the HTTP response and the following data in a single buffer
-
           // Handle back response
           promise.complete(socket);
+
+          // Redeliver pending messages
+          for (Object msg : pending) {
+            pipeline.fireChannelRead(msg);
+          }
         } else {
           promise.fail("Server responded with " + response.statusCode() + " code instead of 200");
         }