FULL PRODUCT VERSION :
Using
JConsole version: 1.6.0_03-b05
Java VM version: Java HotSpot(TM) Client VM, 1.6.0_03-b05

A DESCRIPTION OF THE PROBLEM :
There is no problem using a readwrite role but when you set the role to readonly JConsole gives the error:

Exception in thread "AWT-EventQueue-0" java.lang.SecurityException: Access denied! Invalid access level for requested MBeanServer operation.
at com.sun.jmx.remote.security.MBeanServerFileAccessController.checkAccessLevel(Unknown Source)
at com.sun.jmx.remote.security.MBeanServerFileAccessController.checkWrite(Unknown Source)
at.....

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
setup a plain application on Java 5 or 6 with remote jmx and the 2 default roles controlRole and monitorRole then access with JConsole from Java 6. With controlRole no problems with monitorRole you get the error.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
expected to get access
ACTUAL -
denied access

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "AWT-EventQueue-0" java.lang.SecurityException: Access denied! Invalid access level for requested MBeanServer operation.
at com.sun.jmx.remote.security.MBeanServerFileAccessController.checkAccessLevel(Unknown Source)
at com.sun.jmx.remote.security.MBeanServerFileAccessController.checkWrite(Unknown Source)
at com.sun.jmx.remote.security.MBeanServerAccessController.setAttribute(Unknown Source)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(Unknown Source)
at javax.management.remote.rmi.RMIConnectionImpl.access$200(Unknown Source)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(Unknown Source)
at javax.management.remote.rmi.RMIConnectionImpl.setAttribute(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:142)
at com.sun.jmx.remote.internal.PRef.invoke(Unknown Source)
at javax.management.remote.rmi.RMIConnectionImpl_Stub.setAttribute(Unknown Source)
at javax.management.remote.rmi.RMIConnector$RemoteMBeanServerConnection.setAttribute(RMIConnector.java:921)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.tools.jconsole.ProxyClient$SnapshotInvocationHandler.invoke(ProxyClient.java:982)
at $Proxy0.setAttribute(Unknown Source)
at com.sun.jmx.mbeanserver.MXBeanProxy$SetHandler.invoke(MXBeanProxy.java:120)
at com.sun.jmx.mbeanserver.MXBeanProxy.invoke(MXBeanProxy.java:148)
at javax.management.MBeanServerInvocationHandler.invoke(MBeanServerInvocationHandler.java:248)
at $Proxy2.setThreadCpuTimeEnabled(Unknown Source)
at JTop.setMBeanServerConnection(JTop.java:126)
at JTopPlugin.getTabs(JTopPlugin.java:82)
at sun.tools.jconsole.VMPanel.createPluginTabs(VMPanel.java:640)
at sun.tools.jconsole.VMPanel.propertyChange(VMPanel.java:314)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
at javax.swing.event.SwingPropertyChangeSupport.firePropertyChange(SwingPropertyChangeSupport.java:75)
at javax.swing.event.SwingPropertyChangeSupport$1.run(SwingPropertyChangeSupport.java:80)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
use Java 5 JConsole