# Cannot spy on iOS simulator **URL:** \ **Category:** Bug Report\ **Tags:** katalon-studio, bugs-report\ **Created:** [August 1, 2018, 10:04am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337 "2018-08-01T10:04:32Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Quentin\_Valero](https://avatars.discourse-cdn.com/v4/letter/q/a9adbd/32.png) [@Quentin\_Valero](https://forum.katalon.com/u/Quentin_Valero)\ **Post date:** [August 1, 2018, 10:04am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/1 "2018-08-01T10:04:32Z")
Hello, I am using Katalon 5.5. I want to spy my iOS app on iOS simulator but when I launch it I have following error: > Failed to execute runnable (org.eclipse.core.runtime.AssertionFailedException: null argument:) This is the stacktrace I have in logs: ```auto !ENTRY org.eclipse.e4.ui.workbench 4 0 2018-08-01 11:50:01.664!MESSAGE !STACK 0Root exception:org.eclipse.swt.SWTException: Failed to execute runnable (org.eclipse.core.runtime.AssertionFailedException: null argument:) at org.eclipse.swt.SWT.error(SWT.java:4533) at org.eclipse.swt.SWT.error(SWT.java:4448) at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:255) at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:145) at org.eclipse.swt.widgets.Display.syncExec(Display.java:4814) at org.eclipse.e4.ui.internal.workbench.swt.E4Application$1.syncExec(E4Application.java:211) at com.kms.katalon.composer.components.services.UISynchronizeService.syncExec(UISynchronizeService.java:26) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog$15.refreshTreeElements(MobileObjectSpyDialog.java:912) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog$15.run(MobileObjectSpyDialog.java:893) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:119)Caused by: org.eclipse.core.runtime.AssertionFailedException: null argument: at org.eclipse.core.runtime.Assert.isNotNull(Assert.java:85) at org.eclipse.core.runtime.Assert.isNotNull(Assert.java:73) at org.eclipse.jface.viewers.StructuredViewer.assertElementsNotNull(StructuredViewer.java:586) at org.eclipse.jface.viewers.StructuredViewer.getRawChildren(StructuredViewer.java:1002) at org.eclipse.jface.viewers.ColumnViewer.getRawChildren(ColumnViewer.java:701) at org.eclipse.jface.viewers.AbstractTreeViewer.getRawChildren(AbstractTreeViewer.java:1349) at org.eclipse.jface.viewers.TreeViewer.getRawChildren(TreeViewer.java:341) at org.eclipse.jface.viewers.StructuredViewer.getFilteredChildren(StructuredViewer.java:907) at org.eclipse.jface.viewers.AbstractTreeViewer.getSortedChildren(AbstractTreeViewer.java:621) at org.eclipse.jface.viewers.AbstractTreeViewer.lambda$0(AbstractTreeViewer.java:817) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:795) at org.eclipse.jface.viewers.TreeViewer.createChildren(TreeViewer.java:596) at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:766) at org.eclipse.jface.viewers.AbstractTreeViewer.internalInitializeTree(AbstractTreeViewer.java:1538) at org.eclipse.jface.viewers.TreeViewer.internalInitializeTree(TreeViewer.java:772) at org.eclipse.jface.viewers.AbstractTreeViewer.lambda$1(AbstractTreeViewer.java:1523) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1458) at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:354) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1419) at org.eclipse.jface.viewers.CheckboxTreeViewer.preservingSelection(CheckboxTreeViewer.java:409) at org.eclipse.jface.viewers.AbstractTreeViewer.inputChanged(AbstractTreeViewer.java:1517) at org.eclipse.jface.viewers.ContentViewer.setInput(ContentViewer.java:286) at org.eclipse.jface.viewers.StructuredViewer.setInput(StructuredViewer.java:1696) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog$15$3.run(MobileObjectSpyDialog.java:916) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:182) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4032) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3708) at org.eclipse.jface.operation.ModalContext$ModalContextThread.block(ModalContext.java:165) at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:369) at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:481) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog.captureObjectAction(MobileObjectSpyDialog.java:946) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog.startObjectInspectorAction(MobileObjectSpyDialog.java:1005) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog.access$11(MobileObjectSpyDialog.java:978) at com.kms.katalon.composer.mobile.objectspy.dialog.MobileObjectSpyDialog$12.widgetSelected(MobileObjectSpyDialog.java:722) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:249) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4256) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1501) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1524) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1509) at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1313) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4080) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3706) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1121) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1022) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:150) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:693) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:610) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148) at com.kms.katalon.core.application.Application.internalRunGUI(Application.java:115) at com.kms.katalon.core.application.Application.runGUI(Application.java:100) at com.kms.katalon.core.application.Application.start(Application.java:60) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610) at org.eclipse.equinox.launcher.Main.run(Main.java:1519) ``` Does anyone already faced this issue? ---
**Author:** ![Quentin\_Valero](https://avatars.discourse-cdn.com/v4/letter/q/a9adbd/32.png) [@Quentin\_Valero](https://forum.katalon.com/u/Quentin_Valero)\ **Post date:** [August 3, 2018, 1:17pm UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/2 "2018-08-03T13:17:12Z")
Hello, anyone can help with this issue? It is really blocking the use of Katalon ---
**Author:** ![Zarashima](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/zarashima/32/928_2.png) [@Zarashima](https://forum.katalon.com/u/Zarashima)\ **Post date:** [August 6, 2018, 3:01am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/3 "2018-08-06T03:01:25Z")
Please provide more details how you use it ---
**Author:** ![Quentin\_Valero](https://avatars.discourse-cdn.com/v4/letter/q/a9adbd/32.png) [@Quentin\_Valero](https://forum.katalon.com/u/Quentin_Valero)\ **Post date:** [August 6, 2018, 7:15am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/4 "2018-08-06T07:15:03Z")
I have built my application with xcodebuild in command line with parameter: -destination ‘generic/platform=iOS Simulator’ Then I use Mobile Spy, one of my simulator and select my generated .app file. Katalon is launching the simulator and thenI have this issue. Spy tool is launched (Start button is greyed out, and Stop button is enabled) but I can’t spy on my mobile app due to this error ---
**Author:** ![Chris\_Trevarthen](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/chris_trevarthen/32/358_2.png) [@Chris\_Trevarthen](https://forum.katalon.com/u/Chris_Trevarthen)\ **Post date:** [December 12, 2018, 4:43am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/5 "2018-12-12T04:43:00Z")
Usually, the SWTException is thrown by Katalon or the underlying Eclipse IDE on which it’s built. In my experience, there’s not much that you can do to fix this, other than closing your project and restarting Katalon, or uninstalling and reinstalling Katalon Studio. For more info on [SWTExceptions](https://wiki.eclipse.org/FAQ_Why_do_I_get_an_invalid_thread_access_exception%3F). Sorry I can’t be of more help, Chris ---
**Author:** ![system](https://europe1.discourse-cdn.com/katalon/original/3X/d/5/d55596ab02785a255798e87ede769734747b30c4.svg) [@system](https://forum.katalon.com/u/system)\ **Post date:** [December 12, 2019, 2:33am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/6 "2019-12-12T02:33:36Z")
Automatically bumped on December 12, 2019, 2:33am UTC ---
**Author:** ![system](https://europe1.discourse-cdn.com/katalon/original/3X/d/5/d55596ab02785a255798e87ede769734747b30c4.svg) [@system](https://forum.katalon.com/u/system)\ **Post date:** [December 11, 2020, 1:39am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/7 "2020-12-11T01:39:50Z")
Automatically bumped on December 11, 2020, 1:39am UTC ---
**Author:** ![Jass](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/jass/32/9588_2.png) [@Jass](https://forum.katalon.com/u/Jass)\ **Post date:** [December 11, 2020, 2:40am UTC](https://forum.katalon.com/t/cannot-spy-on-ios-simulator/12337/8 "2020-12-11T02:40:53Z")
Closed on December 11, 2020, 2:40am UTC