diff --git a/netty-socketio-core/src/main/java/com/socketio4j/socketio/SocketIOServer.java b/netty-socketio-core/src/main/java/com/socketio4j/socketio/SocketIOServer.java
index 0d3a6561..df148a82 100644
--- a/netty-socketio-core/src/main/java/com/socketio4j/socketio/SocketIOServer.java
+++ b/netty-socketio-core/src/main/java/com/socketio4j/socketio/SocketIOServer.java
@@ -608,8 +608,10 @@ public Future<Void> startAsync() {
                             int actualPort = local.getPort();
                             configCopy.setPort(actualPort);
                             configuration.setPort(actualPort);
-                        } catch (Exception ignore) {
+                        } catch (Exception e) {
                             // keep configured port if localAddress is not InetSocketAddress
+                            log.debug("Could not resolve actual bound port, keeping configured port {}",
+                                    configCopy.getPort(), e);
                         }
                     }
                     serverStatus.set(ServerStatus.STARTED);
@@ -618,7 +620,7 @@ public Future<Void> startAsync() {
                     fireAfterStart();
                 } else {
                     serverStatus.set(ServerStatus.INIT);
-                    log.error("Failed to start server on port {}", configCopy.getPort());
+                    log.error("Failed to start server on port {}", configCopy.getPort(), future.cause());
                     cleanUpResources(false);
                 }
             });
diff --git a/netty-socketio-core/src/main/java/com/socketio4j/socketio/handler/EncoderHandler.java b/netty-socketio-core/src/main/java/com/socketio4j/socketio/handler/EncoderHandler.java
index a697d231..65dc23c1 100644
--- a/netty-socketio-core/src/main/java/com/socketio4j/socketio/handler/EncoderHandler.java
+++ b/netty-socketio-core/src/main/java/com/socketio4j/socketio/handler/EncoderHandler.java
@@ -110,8 +110,9 @@ private void readVersion() throws IOException {
                     version = name + "/" + attrs.getValue("Bundle-Version");
                     break;
                 }
-            } catch (IOException E) {
-                // skip it
+            } catch (IOException e) {
+                // A single unreadable manifest must not prevent reading the others
+                log.debug("Skipping unreadable MANIFEST.MF while resolving version header", e);
             }
         }
     }
diff --git a/netty-socketio-core/src/main/java/com/socketio4j/socketio/transport/PollingTransport.java b/netty-socketio-core/src/main/java/com/socketio4j/socketio/transport/PollingTransport.java
index 1e34aeae..f5524c69 100644
--- a/netty-socketio-core/src/main/java/com/socketio4j/socketio/transport/PollingTransport.java
+++ b/netty-socketio-core/src/main/java/com/socketio4j/socketio/transport/PollingTransport.java
@@ -128,6 +128,11 @@ private void handleMessage(FullHttpRequest req, UUID sessionId, QueryStringDecod
             String origin = req.headers().get(HttpHeaderNames.ORIGIN);
             if (queryDecoder.parameters().containsKey("disconnect")) {
                 ClientHead client = clientsBox.get(sessionId);
+                if (client == null) {
+                    log.error("{} is not registered. Closing connection", sessionId);
+                    sendError(ctx);
+                    return;
+                }
                 client.onChannelDisconnect();
                 ctx.channel().writeAndFlush(new XHRPostMessage(origin, sessionId));
             } else if (HttpMethod.POST.equals(req.method())) {