WebChat broken after 4.1.6 upgrade

Has anyone come across this issue? I upgraded to 4.1.6 from 4.0.1, and the webchat service doesn’t seem to work any longer. here is a copy of the log:

An exception occurred while loading plugin ‘fastpath’:
java.lang.NoSuchMethodError: org.jivesoftware.openfire.net.SASLAuthentication.isSharedSecretAllowed()Z
at org.jivesoftware.xmpp.workgroup.WorkgroupManager.start(WorkgroupManager.java:216)
at org.jivesoftware.openfire.component.InternalComponentManager.addComponent(InternalComponentManager.java:159)
at org.jivesoftware.openfire.fastpath.FastpathPlugin.workgroupManagerStart(FastpathPlugin.java:100)
at org.jivesoftware.openfire.fastpath.FastpathPlugin.initializePlugin(FastpathPlugin.java:80)
at org.jivesoftware.openfire.container.PluginManager.loadPlugin(PluginManager.java:415)
at org.jivesoftware.openfire.container.PluginMonitor$MonitorTask$4.call(PluginMonitor.java:276)
at org.jivesoftware.openfire.container.PluginMonitor$MonitorTask$4.call(PluginMonitor.java:264)