diff --git a/broker/src/main/java/io/moquette/server/netty/NettyMQTTHandler.java b/broker/src/main/java/io/moquette/server/netty/NettyMQTTHandler.java
index 08158181..c4091e5a 100644
--- a/broker/src/main/java/io/moquette/server/netty/NettyMQTTHandler.java
+++ b/broker/src/main/java/io/moquette/server/netty/NettyMQTTHandler.java
@@ -42,7 +42,7 @@ public class NettyMQTTHandler extends ChannelInboundHandlerAdapter {
     public void channelRead(ChannelHandlerContext ctx, Object message) {
         MqttMessage msg = (MqttMessage) message;
         MqttMessageType messageType = msg.fixedHeader().messageType();
-        LOG.debug("Processing MQTT message, type={}", messageType);
+        LOG.debug("Processing MQTT message, type: {}", messageType);
         try {
             switch (messageType) {
                 case CONNECT:
@@ -83,20 +83,18 @@ public class NettyMQTTHandler extends ChannelInboundHandlerAdapter {
                     ctx.writeAndFlush(pingResp).addListener(CLOSE_ON_FAILURE);
                     break;
                 default:
-                    LOG.error("Unkonwn MessageType:{}", messageType);
+                    LOG.error("Unknown MessageType: {}", messageType);
                     break;
             }
         } catch (Throwable ex) {
-            LOG.error("Exception was caught while processing MQTT message, {}", ex.getCause(), ex);
             ctx.fireExceptionCaught(ex);
-            ctx.close().addListener(CLOSE_ON_FAILURE);
         } finally {
             ReferenceCountUtil.release(msg);
         }
     }
 
     @Override
-    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
+    public void channelInactive(ChannelHandlerContext ctx) {
         String clientID = NettyUtils.clientID(ctx.channel());
         if (clientID != null && !clientID.isEmpty()) {
             LOG.info("Notifying connection lost event. MqttClientId = {}", clientID);
@@ -106,14 +104,14 @@ public class NettyMQTTHandler extends ChannelInboundHandlerAdapter {
     }
 
     @Override
-    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        LOG.error("An unexpected exception was caught while processing MQTT message. Closing Netty channel. CId={}, " +
-            "cause={}, errorMessage={}", NettyUtils.clientID(ctx.channel()), cause.getCause(), cause.getMessage());
+    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
+        LOG.error("Unexpected exception while processing MQTT message. Closing Netty channel. CId={}",
+            NettyUtils.clientID(ctx.channel()), cause);
         ctx.close().addListener(CLOSE_ON_FAILURE);
     }
 
     @Override
-    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
+    public void channelWritabilityChanged(ChannelHandlerContext ctx) {
         if (ctx.channel().isWritable()) {
             m_processor.notifyChannelWritable(ctx.channel());
         }
diff --git a/broker/src/main/java/io/moquette/spi/impl/SessionsRepository.java b/broker/src/main/java/io/moquette/spi/impl/SessionsRepository.java
index 8ccde278..3f0c091c 100644
--- a/broker/src/main/java/io/moquette/spi/impl/SessionsRepository.java
+++ b/broker/src/main/java/io/moquette/spi/impl/SessionsRepository.java
@@ -27,6 +27,7 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
@@ -48,7 +49,7 @@ public class SessionsRepository {
     private final ISessionsStore sessions;
     private ISubscriptionsStore subscriptionsStore;
     private ScheduledExecutorService scheduler;
-    private final Map<String, ClientSession> sessionsCache = new ConcurrentHashMap<>();
+    private final ConcurrentMap<String, ClientSession> sessionsCache = new ConcurrentHashMap<>();
 
     public SessionsRepository(ISessionsStore sessionsStore, ScheduledExecutorService scheduler) {
         this.sessions = sessionsStore;