Since updating from 4.7.2 to mendix version 4.8.3 we have been experiencing issues with the export to excel button. This issue will occur when your datagrid has a column to a date attribute of another object The following error apears in the log when clicking on the button: Exception in async action 'null': java.lang.NullPointerException at org.apache.poi.ss.util.DateFormatConverter.convert(DateFormatConverter.java:341) at ll.a(SourceFile:192) at ll.a(SourceFile:165) at ll.a(SourceFile:76) at ll.a(SourceFile:53) at com.mendix.modules.exportmanager.ExportManagerModule.generateXLS(SourceFile:71) at gq.a(SourceFile:264) at gq.a(SourceFile:123) at gq.a(SourceFile:81) at gq$a.a(SourceFile:443) at gq$a.execute(SourceFile:421) at hL.execute(SourceFile:26) at com.mendix.core.actionmanagement.CoreAction.a(SourceFile:478) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:463) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:662) The issue is affecting new and old export to excel buttons, and some of our employees are unable to do their work and reporting. Further more I believe this issue is causing issues with the application's garbage collector and memory. A user tried to invoke the action a couple of times and received the above async error, and then the application became unresponsive. When I stopped the service, the following error appeared in the log: Garbage collection failed: java.util.NoSuchElementException: None.get at scala.None$.get(Option.scala:274) at scala.None$.get(Option.scala:272) at com.mendix.core.cache.MxObjectCache.a(SourceFile:50) at id.<init>(SourceFile:20) at com.mendix.externalinterface.connector.RequestDispatching$Worker.b(SourceFile:231) at com.mendix.externalinterface.connector.RequestDispatching$Worker.a(SourceFile:203) at com.mendix.externalinterface.connector.RequestDispatching$Worker$a.a(SourceFile:196) at com.mendix.externalinterface.connector.RequestDispatching$Worker$a.apply(SourceFile:183) at akka.actor.Actor$class.apply(Actor.scala:545) at com.mendix.externalinterface.connector.RequestDispatching$Worker.apply(SourceFile:179) at akka.actor.LocalActorRef.invoke(ActorRef.scala:910) at akka.dispatch.MessageInvocation.invoke(MessageHandling.scala:25) at akka.dispatch.ExecutableMailbox$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(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) at akka.dispatch.MonitorableThread.run(ThreadPoolBuilder.scala:192)
Can you reproduce this issue in a simple test project? I would suggest filing a support request including such a project so that we can look at your issue.
It looks like the same issue as https://forum.mendix.com/questions/5029/Export-to-Excel-error-Exception-in-async-action-null
We have a ticket for this (minus the garbage collection error) with Ticket id: 101274