diff --git a/jetty-server/src/main/java/org/eclipse/jetty/server/Response.java b/jetty-server/src/main/java/org/eclipse/jetty/server/Response.java
index 1ec2f2eae0e..8f1d16e5a03 100644
--- a/jetty-server/src/main/java/org/eclipse/jetty/server/Response.java
+++ b/jetty-server/src/main/java/org/eclipse/jetty/server/Response.java
@@ -1114,8 +1114,10 @@ public class Response implements HttpServletResponse
     @Override
     public void setBufferSize(int size)
     {
-        if (isCommitted() || getContentCount() > 0)
-            throw new IllegalStateException("cannot set buffer size when response is committed or written to");
+        if (isCommitted())
+            throw new IllegalStateException("cannot set buffer size after response is in committed state");
+        if (getContentCount() > 0)
+            throw new IllegalStateException("cannot set buffer size after response has " + getContentCount() + " bytes already written");
         if (size < __MIN_BUFFER_SIZE)
             size = __MIN_BUFFER_SIZE;
         _out.setBufferSize(size);
diff --git a/jetty-start/src/main/java/org/eclipse/jetty/start/Main.java b/jetty-start/src/main/java/org/eclipse/jetty/start/Main.java
index 3b838210b42..863c4486ed2 100644
--- a/jetty-start/src/main/java/org/eclipse/jetty/start/Main.java
+++ b/jetty-start/src/main/java/org/eclipse/jetty/start/Main.java
@@ -18,6 +18,8 @@
 
 package org.eclipse.jetty.start;
 
+import static org.eclipse.jetty.start.UsageException.ERR_BAD_GRAPH;
+import static org.eclipse.jetty.start.UsageException.ERR_BAD_STOP_PROPS;
 import static org.eclipse.jetty.start.UsageException.ERR_INVOKE_MAIN;
 import static org.eclipse.jetty.start.UsageException.ERR_NOT_STOPPED;
 import static org.eclipse.jetty.start.UsageException.ERR_UNKNOWN;
@@ -492,19 +494,38 @@ public class Main
 
     private void doStop(StartArgs args)
     {
-        String stopHost = args.getProperties().getString("STOP.HOST");
-        int stopPort = Integer.parseInt(args.getProperties().getString("STOP.PORT"));
-        String stopKey = args.getProperties().getString("STOP.KEY");
-
-        if (args.getProperties().getString("STOP.WAIT") != null)
+        Props.Prop stopHostProp = args.getProperties().getProp("STOP.HOST", true);
+        Props.Prop stopPortProp = args.getProperties().getProp("STOP.PORT", true);
+        Props.Prop stopKeyProp = args.getProperties().getProp("STOP.KEY", true);
+        Props.Prop stopWaitProp = args.getProperties().getProp("STOP.WAIT", true);
+        
+        String stopHost = "127.0.0.1";
+        int stopPort = -1;
+        String stopKey = "";
+    
+        if (stopHostProp != null)
         {
-            int stopWait = Integer.parseInt(args.getProperties().getString("STOP.WAIT"));
+            stopHost = stopHostProp.value;
+        }
+    
+        if (stopPortProp != null)
+        {
+            stopPort = Integer.parseInt(stopPortProp.value);
+        }
+        
+        if(stopKeyProp != null)
+        {
+            stopKey = stopKeyProp.value;
+        }
 
-            stop(stopHost,stopPort,stopKey,stopWait);
+        if (stopWaitProp != null)
+        {
+            int stopWait = Integer.parseInt(stopWaitProp.value);
+            stop(stopHost, stopPort, stopKey, stopWait);
         }
         else
         {
-            stop(stopHost,stopPort,stopKey);
+            stop(stopHost, stopPort, stopKey);
         }
     }
 
@@ -522,19 +543,22 @@ public class Main
     public void stop(String host, int port, String key, int timeout)
     {
         if (host==null || host.length()==0)
-            host="127.0.0.1";
+        {
+            host = "127.0.0.1";
+        }
         
         try
         {
-            if (port <= 0)
+            if ( (port <= 0) || (port > 65535) )
             {
-                StartLog.error("STOP.PORT system property must be specified");
+                System.err.println("STOP.PORT property must be specified with a valid port number");
+                usageExit(ERR_BAD_STOP_PROPS);
             }
             if (key == null)
             {
                 key = "";
-                StartLog.info("STOP.KEY system property must be specified");
-                StartLog.info("Using empty key");
+                System.err.println("STOP.KEY property must be specified");
+                System.err.println("Using empty key");
             }
 
             try (Socket s = new Socket(InetAddress.getByName(host),port))
diff --git a/jetty-start/src/main/java/org/eclipse/jetty/start/UsageException.java b/jetty-start/src/main/java/org/eclipse/jetty/start/UsageException.java
index 914533d0128..75f124bd82f 100644
--- a/jetty-start/src/main/java/org/eclipse/jetty/start/UsageException.java
+++ b/jetty-start/src/main/java/org/eclipse/jetty/start/UsageException.java
@@ -29,6 +29,7 @@ public class UsageException extends RuntimeException
     public static final int ERR_NOT_STOPPED = -4;
     public static final int ERR_BAD_ARG = -5;
     public static final int ERR_BAD_GRAPH = -6;
+    public static final int ERR_BAD_STOP_PROPS = -7;
     public static final int ERR_UNKNOWN = -9;
     private int exitCode;