diff --git a/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpSenderOverHTTP.java b/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpSenderOverHTTP.java
index 99d84198dab..b3e88b836df 100644
--- a/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpSenderOverHTTP.java
+++ b/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpSenderOverHTTP.java
@@ -35,12 +35,12 @@ import org.eclipse.jetty.io.EndPoint;
 import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.IteratingCallback;
-import org.eclipse.jetty.util.log.Log;
-import org.eclipse.jetty.util.log.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class HttpSenderOverHTTP extends HttpSender
 {
-    private static final Logger LOG = Log.getLogger(HttpSenderOverHTTP.class);
+    private static final Logger LOG = LoggerFactory.getLogger(HttpSenderOverHTTP.class);
 
     private final HttpGenerator generator = new HttpGenerator();
     private boolean shutdown;
diff --git a/jetty-client/src/main/java/org/eclipse/jetty/client/http/ProtocolHttpUpgrader.java b/jetty-client/src/main/java/org/eclipse/jetty/client/http/ProtocolHttpUpgrader.java
index 6487c35f582..688b424ac18 100644
--- a/jetty-client/src/main/java/org/eclipse/jetty/client/http/ProtocolHttpUpgrader.java
+++ b/jetty-client/src/main/java/org/eclipse/jetty/client/http/ProtocolHttpUpgrader.java
@@ -35,8 +35,8 @@ import org.eclipse.jetty.http.HttpHeader;
 import org.eclipse.jetty.io.EndPoint;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.Promise;
-import org.eclipse.jetty.util.log.Log;
-import org.eclipse.jetty.util.log.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * <p>A HttpUpgrader that upgrades to a given protocol.</p>
@@ -47,7 +47,7 @@ import org.eclipse.jetty.util.log.Logger;
  */
 public class ProtocolHttpUpgrader implements HttpUpgrader
 {
-    private static final Logger LOG = Log.getLogger(ProtocolHttpUpgrader.class);
+    private static final Logger LOG = LoggerFactory.getLogger(ProtocolHttpUpgrader.class);
 
     private final HttpDestination destination;
     private final String protocol;
diff --git a/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/ClientConnectionFactoryOverHTTP2.java b/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/ClientConnectionFactoryOverHTTP2.java
index 5e7a63233e0..1f17ae4bfcd 100644
--- a/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/ClientConnectionFactoryOverHTTP2.java
+++ b/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/ClientConnectionFactoryOverHTTP2.java
@@ -87,6 +87,9 @@ public class ClientConnectionFactoryOverHTTP2 extends ContainerLifeCycle impleme
                     // handle the HTTP/2 response to the upgrade request.
                     promise.succeeded(connection);
                     connection.upgrade(context);
+                    // The connection can be used only after the upgrade that
+                    // creates stream #1 corresponding to the HTTP/1.1 upgrade
+                    // request, otherwise other requests can steal id #1.
                     destination.accept(connection);
                 }
 
diff --git a/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpSenderOverHTTP2.java b/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpSenderOverHTTP2.java
index 8f33a65626d..b3aeacaa3de 100644
--- a/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpSenderOverHTTP2.java
+++ b/jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpSenderOverHTTP2.java
@@ -37,12 +37,12 @@ import org.eclipse.jetty.http2.frames.DataFrame;
 import org.eclipse.jetty.http2.frames.HeadersFrame;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.Promise;
-import org.eclipse.jetty.util.log.Log;
-import org.eclipse.jetty.util.log.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class HttpSenderOverHTTP2 extends HttpSender
 {
-    private static final Logger LOG = Log.getLogger(HttpSenderOverHTTP2.class);
+    private static final Logger LOG = LoggerFactory.getLogger(HttpSenderOverHTTP2.class);
 
     public HttpSenderOverHTTP2(HttpChannelOverHTTP2 channel)
     {