I migrated a project from 2.3.3 to 2.5.3. I got the following xpaths in a java action: List<IMendixObject> iVoorstelWel = Core.retrieveXPathQuery(context, "//" + Productievoorstel.getType() + "[AWBZ.Productievoorstel_Offerte='" + offerteObj.getGUID() + "'][AWBZ.Productievoorstel_Project/OfferteConfiguratie.Project]", Integer.MAX_VALUE, 0, sortVoorstel, 1); List<IMendixObject> iVoorstelNiet = Core.retrieveXPathQuery(context, "//" + Productievoorstel.getType() + "[AWBZ.Productievoorstel_Offerte='" + offerteObj.getGUID() + "'][not(AWBZ.Productievoorstel_Project/OfferteConfiguratie.Project)]", Integer.MAX_VALUE, 0, sortVoorstel, 1); The first one is working propperly but the second throws a stacktrace. Both XPath queries used to work in the older version 2.3.3, is something changed in 2.5.3? com.mendix.core.CoreException: Exception occurred in action 'Microflow [AWBZ.Export_OfferteFlow]', all database changes executed by this action were rolled back at com.mendix.core.actionmanagement.CoreAction.d(SourceFile:553) Caused by: com.mendix.core.CoreException: Exception occurred in microflow 'AWBZ.Export_OfferteFlow' for activity 'Call 'Export_Offerte'', all database changes executed by this microflow were rolled back at kP.b(SourceFile:251) Caused by: com.mendix.core.CoreException: kO: An exception has occurred for the following request(s): jE (depth = 1, amount = 2147483647): //AWBZ.Productievoorstel[AWBZ.Productievoorstel_Offerte='ID_281986077820082'][not(AWBZ.Productievoorstel_Project/OfferteConfiguratie.Project)] at it.b(SourceFile:167) Caused by: kO: An exception has occurred for the following request(s): jE (depth = 1, amount = 2147483647): //AWBZ.Productievoorstel[AWBZ.Productievoorstel_Offerte='ID_281986077820082'][not(AWBZ.Productievoorstel_Project/OfferteConfiguratie.Project)] Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to ar at D.a(SourceFile:539) at D.a(SourceFile:366) at D.a(SourceFile:135) at gl.a(SourceFile:92) at lx.a(SourceFile:69) at jC.a(SourceFile:47) at jm.a(SourceFile:222) at fG.b(SourceFile:121) at fG.a(SourceFile:63) at iu.a(SourceFile:58) at iu.executeAction(SourceFile:20) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:49) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:473) at it.b(SourceFile:155) at com.mendix.core.Core.retrieveXPathQuery(SourceFile:819) at awbz.actions.Export_Offerte.executeAction(Export_Offerte.java:76) at awbz.actions.Export_Offerte.executeAction(Export_Offerte.java:1) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:49) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:473) at it.b(SourceFile:155) at com.mendix.core.Core.execute(SourceFile:191) at hi.a(SourceFile:70) at kP.a(SourceFile:66) at eO.executeAction(SourceFile:96) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:49) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:473) at it.b(SourceFile:155) at com.mendix.core.Core.execute(SourceFile:191) at dw.execute(SourceFile:183) at ju.a(SourceFile:299) at ju.a(SourceFile:230) at ju.processRequest(SourceFile:174) at fC.a(SourceFile:71) at com.mendix.core.MxRuntime.processRequest(SourceFile:916) at com.mendix.m2ee.server.handler.RuntimeHandler.handle(RuntimeHandler.java:42) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:113) at org.eclipse.jetty.server.Server.handle(Server.java:334) at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:559) at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpConnection.java:1007) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:747) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:209) at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:406) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:462) at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:436) at java.lang.Thread.run(Thread.java:662)