We encounter the folowing error: What can cause this error? com.mendix.systemwideinterfaces.MendixRuntimeException: java.lang.IllegalArgumentException: Session '9118a327-0284-43e5-a6fe-b506b2e210b9' is not managed by the session manager Stacktrace: com.mendix.systemwideinterfaces.MendixRuntimeException: java.lang.IllegalArgumentException: Session '9118a327-0284-43e5-a6fe-b506b2e210b9' is not managed by the session manager at com.mendix.util.classloading.Runner.doRunUsingClassLoaderOf(Runner.java:36) Caused by: java.lang.IllegalArgumentException: Session '9118a327-0284-43e5-a6fe-b506b2e210b9' is not managed by the session manager at com.mendix.core.session.SessionManager.destroy(SessionManager.java:246) at com.mendix.core.session.SessionManager.destroy(SessionManager.java:241) at com.mendix.core.component.InternalCore.logout(InternalCore.java:2039) at com.mendix.core.Core.logout(Core.java:1370) at wshandler.implementation.WSHandler.processRequest(WSHandler.java:136) at com.mendix.externalinterface.connector.MxRuntimeConnector$1.execute(MxRuntimeConnector.java:69) at com.mendix.externalinterface.connector.MxRuntimeConnector$1.execute(MxRuntimeConnector.java:66) at com.mendix.util.classloading.Runner.doRunUsingClassLoaderOf(Runner.java:32) at com.mendix.externalinterface.connector.MxRuntimeConnector.processRequest(MxRuntimeConnector.java:72) at com.mendix.core.impl.MxRuntimeImpl.processRequest(MxRuntimeImpl.java:720) at com.mendix.m2ee.appcontainer.server.handler.RuntimeHandler.handle(RuntimeHandler.java:41) at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:52) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116) at org.eclipse.jetty.server.Server.handle(Server.java:368) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489) at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:953) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1014) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:861) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:628) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543) at java.lang.Thread.run(Unknown Source)