It happens rarely if you create a new wiki.
2016-11-08 13:17:12,800 [ajp-nio-8009-exec-48] ERROR OLATRuntimeException - OLAT::ERROR ^%^ N1-E36 https://f.xyz.de/auth/RepositoryEntry/1306624007 Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36 ^%^ **RedScreen** null <dispatchinfo> <componentinfo> <compname>ffo_main_null</compname> <compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass> <extendedinfo>n/a</extendedinfo> <event> <class>org.olat.core.gui.control.Event</class> <command>validation ok</command> <tostring>com:validation ok,org.olat.core.gui.control.Event@d62b3f02</tostring> </event> </componentinfo> <controllerinfo> <controllername>org.olat.resource.accesscontrol.provider.free.ui.FreeAccessController</controllername> <controllername>org.olat.resource.accesscontrol.ui.AccessListController</controllername> <controllername>org.olat.repository.ui.RepositoryEntryRuntimeController</controllername> <controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername> </controllerinfo> </dispatchinfo> >>> stack of 1.cause::org.olat.core.logging.OLATRuntimeException: null -> at org.olat.core.gui.exception.ExceptionWindowController.<init>(ExceptionWindowController.java:116) at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:57) at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:46) at org.olat.core.gui.components.Window.dispatchRequest(Window.java:547) at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:240) at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193) at org.olat.dispatcher.AuthenticatedDispatcher.processValidDispatchURI(AuthenticatedDispatcher.java:275) at org.olat.dispatcher.AuthenticatedDispatcher.execute(AuthenticatedDispatcher.java:192) at org.olat.core.servlets.OpenOLATServlet.executeUserRequest(OpenOLATServlet.java:289) at org.olat.core.servlets.OpenOLATServlet.doPost(OpenOLATServlet.java:232) at javax.servlet.http.HttpServlet.service(HttpServlet.java:644) >>> stack of 2.cause::java.lang.NullPointerException: null -> at org.olat.core.util.session.UserSessionManager.getUserSession(UserSessionManager.java:110) at org.olat.core.util.session.UserSessionManager.getUserSession(UserSessionManager.java:138) at org.olat.core.gui.UserRequestImpl.getUserSession(UserRequestImpl.java:151) at org.olat.core.gui.UserRequestImpl.getIdentity(UserRequestImpl.java:180) at org.olat.repository.handlers.WikiHandler$1.create(WikiHandler.java:254) at org.olat.repository.ui.RepositoryEntryRuntimeController.launchContent(RepositoryEntryRuntimeController.java:940) at org.olat.repository.ui.RepositoryEntryRuntimeController.event(RepositoryEntryRuntimeController.java:558) at org.olat.core.gui.control.DefaultController$1.run(DefaultController.java:246) at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108) at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:243) at org.olat.core.gui.control.DefaultController.fireEvent(DefaultController.java:190)