Exception:
    <pre>
java.lang.NullPointerException: Cannot invoke "org.jivesoftware.openfire.user.User.getUsername()" because the return value of "org.jivesoftware.util.WebManager.getUser()" is null<br>	at org.jivesoftware.openfire.admin.decorators.main_jsp._jspService(main_jsp.java:218)<br>	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:65)<br>	at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)<br>	at org.eclipse.jetty.ee8.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1164)<br>	at org.eclipse.jetty.ee8.servlet.ServletHolder.handle(ServletHolder.java:653)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1377)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler.doHandle(ServletHandler.java:454)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:119)<br>	at org.eclipse.jetty.ee8.security.SecurityHandler.handle(SecurityHandler.java:509)<br>	at org.eclipse.jetty.ee8.nested.HandlerWrapper.handle(HandlerWrapper.java:108)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:183)<br>	at org.eclipse.jetty.ee8.nested.SessionHandler.doHandle(SessionHandler.java:519)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:181)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler.doHandle(ContextHandler.java:891)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:152)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler.doScope(ServletHandler.java:423)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150)<br>	at org.eclipse.jetty.ee8.nested.SessionHandler.doScope(SessionHandler.java:503)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler.doScope(ContextHandler.java:830)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:117)<br>	at org.eclipse.jetty.ee8.nested.Dispatcher.include(Dispatcher.java:105)<br>	at com.opensymphony.sitemesh.compatability.OldDecorator2NewDecorator.render(OldDecorator2NewDecorator.java:46)<br>	at com.opensymphony.sitemesh.webapp.decorator.BaseWebAppDecorator.render(BaseWebAppDecorator.java:33)<br>	at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:93)<br>	at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1351)<br>	at org.jivesoftware.admin.CacheControlFilter.doFilter(CacheControlFilter.java:87)<br>	at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:177)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1351)<br>	at org.jivesoftware.admin.ContentSecurityPolicyFilter.doFilter(ContentSecurityPolicyFilter.java:53)<br>	at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1351)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler.doHandle(ServletHandler.java:454)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:119)<br>	at org.eclipse.jetty.ee8.security.SecurityHandler.handle(SecurityHandler.java:497)<br>	at org.eclipse.jetty.ee8.nested.HandlerWrapper.handle(HandlerWrapper.java:108)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:183)<br>	at org.eclipse.jetty.ee8.nested.SessionHandler.doHandle(SessionHandler.java:519)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:181)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler.doHandle(ContextHandler.java:891)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:152)<br>	at org.eclipse.jetty.ee8.servlet.ServletHandler.doScope(ServletHandler.java:423)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150)<br>	at org.eclipse.jetty.ee8.nested.SessionHandler.doScope(SessionHandler.java:503)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler.doScope(ContextHandler.java:830)<br>	at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:117)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler.handle(ContextHandler.java:1451)<br>	at org.eclipse.jetty.ee8.nested.HttpChannel$RequestDispatchable.dispatch(HttpChannel.java:1294)<br>	at org.eclipse.jetty.ee8.nested.HttpChannel.dispatch(HttpChannel.java:620)<br>	at org.eclipse.jetty.ee8.nested.HttpChannel.handle(HttpChannel.java:460)<br>	at org.eclipse.jetty.ee8.nested.ContextHandler$CoreContextHandler$CoreToNestedHandler.handle(ContextHandler.java:2523)<br>	at org.eclipse.jetty.server.handler.ContextHandler.handle(ContextHandler.java:1102)<br>	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:151)<br>	at org.eclipse.jetty.server.Handler$Sequence.handle(Handler.java:805)<br>	at org.eclipse.jetty.server.Server.handle(Server.java:182)<br>	at org.eclipse.jetty.server.internal.HttpChannelState$HandlerInvoker.run(HttpChannelState.java:772)<br>	at org.eclipse.jetty.server.internal.HttpConnection.onFillable(HttpConnection.java:415)<br>	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:323)<br>	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)<br>	at org.eclipse.jetty.io.SelectableChannelEndPoint$1.run(SelectableChannelEndPoint.java:53)<br>	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.runTask(AdaptiveExecutionStrategy.java:492)<br>	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.epcRunTask(AdaptiveExecutionStrategy.java:428)<br>	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.consumeTask(AdaptiveExecutionStrategy.java:401)<br>	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.tryProduce(AdaptiveExecutionStrategy.java:255)<br>	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.run(AdaptiveExecutionStrategy.java:204)<br>	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:311)<br>	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:981)<br>	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.doRunJob(QueuedThreadPool.java:1212)<br>	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1166)<br>	at java.base/java.lang.Thread.run(Unknown Source)<br>
    </pre>