As i implemented a richtext editor i have the following error on opening the image select in the Richtext editor. This is my Stacktrace: com.mendix.core.CoreRuntimeException: com.mendix.core.CoreRuntimeException: Exception occurred in action '{"type":"RetrieveXPathAggregateAction","xpath":"undefined(undefined)"}', all database changes executed by this action were rolled back at hC.b(SourceFile:193) Caused by: com.mendix.core.CoreRuntimeException: Exception occurred in action '{"type":"RetrieveXPathAggregateAction","xpath":"undefined(undefined)"}', all database changes executed by this action were rolled back at com.mendix.core.actionmanagement.CoreAction.c(SourceFile:515) Caused by: n: An exception has occurred for the following request(s): fu (depth = -1): undefined(undefined) at x.a(SourceFile:57) Caused by: com.mendix.systemwideinterfaces.MendixRuntimeException: Unsupported aggregate function 'undefined' at jR.c(SourceFile:296) at jR.a(SourceFile:139) at jF.a(SourceFile:27) at fl.a(SourceFile:107) at fl.a(SourceFile:90) at dQ.a(SourceFile:37) at fu.getSuitableRequest(SourceFile:31) at dE.a(SourceFile:63) at x.a(SourceFile:43) at h.a(SourceFile:269) at hr.b(SourceFile:71) at hr.a(SourceFile:46) at hr.executeAction(SourceFile:19) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:57) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:457) at hC.b(SourceFile:182) at com.mendix.core.Core.retrieveXPathQueryAggregate(SourceFile:1501) at gH.execute(SourceFile:44) at iW.a(SourceFile:285) at ja$g.a(SourceFile:126) at ja$g$a.a(SourceFile:118) at ja$g$a.apply(SourceFile:116) at akka.actor.Actor$class.apply(Actor.scala:545) at ja$g.apply(SourceFile:112) at akka.actor.LocalActorRef.invoke(ActorRef.scala:910) at akka.dispatch.MessageInvocation.invoke(MessageHandling.scala:25) at akka.dispatch.ExecutableMailbox$class.processMailbox(ExecutorBasedEventDrivenDispatcher.scala:223) at akka.dispatch.ExecutorBasedEventDrivenDispatcher$$anon$4.processMailbox(ExecutorBasedEventDrivenDispatcher.scala:123) at akka.dispatch.ExecutableMailbox$class.run(ExecutorBasedEventDrivenDispatcher.scala:195) at akka.dispatch.ExecutorBasedEventDrivenDispatcher$$anon$4.run(ExecutorBasedEventDrivenDispatcher.scala:123) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) at akka.dispatch.MonitorableThread.run(ThreadPoolBuilder.scala:192) Does someone know what this stacktrace is meaning? Kind regards, Mike Vermeer