The WIKI field renderer help is not working

An error occurred whilst rendering this message. Please contact the administrators, and inform them of this bug. 
Details: ------- 
java.lang.NullPointerException at org.apache.velocity.context.InternalContextAdapterImpl.get(InternalContextAdapterImpl.java:162) 
  at org.apache.velocity.runtime.parser.node.ASTReference.getVariableValue(ASTReference.java:623)
  at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:151)
  at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:220)
  at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:230)
  at org.apache.velocity.Template.merge(Template.java:256)
  at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:450)
  at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:419)
  at com.atlassian.velocity.DefaultVelocityManager.getEncodedBody(DefaultVelocityManager.java:74)
  at com.atlassian.jira.plugin.webwork.JiraPluginWebworkVelocityServlet.service(JiraPluginWebworkVelocityServlet.java:50)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
  at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
  at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
  at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
  at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:248)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.jira.web.filters.AccessLogFilter.doFilter(AccessLogFilter.java:51)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
  at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
  at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:38)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:177)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
  at com.atlassian.jira.web.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:25)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.jira.web.filters.ActionCleanupDelayFilter.doFilter(ActionCleanupDelayFilter.java:37)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:91)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.jira.web.filters.gzip.GzipFilter.doFilter(GzipFilter.java:72)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:37)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
  at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
  at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) 
  at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
  at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
  at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
  at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
  at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
  at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
  at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
  at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684) at java.lang.Thread.run(Thread.java:595)