Hi, After completing specific things in my app,it is showing the below error message. System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object. at Mendix.Modeler.WebUI.JSEngine.Manager.JsFunctionCache.JsFunctionLruCache`1.TryGet(IList`1 parameters, Result`1& result) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\JsFunctionCache\JsFunctionLruCache.cs:line 20 at Mendix.Modeler.WebUI.JSEngine.Manager.JsFunctionCache.CachedJsFunction`1.GetResult(WidgetObject widgetObject, JsParameter[] additionalArgs) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\JsFunctionCache\CachedJsFunction.cs:line 30 at Mendix.Modeler.WebUI.JSEngine.Manager.WidgetJsExtensionManager.ComputePropertiesView(CustomWidget customWidget, StudioType studioType) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\WidgetJsExtensionManager.cs:line 129 at Mendix.Modeler.WebUI.JSEngine.Manager.WidgetJsExtensionManager.ComputeProperties(WidgetObject element) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\WidgetJsExtensionManager.cs:line 81 at Mendix.Modeler.WebUI.WidgetPackages.CustomWidgetExtensionHelpers.GetPropertyView(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\WidgetPackages\CustomWidgetExtensionHelpers.cs:line 19 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetProperty.GetCaption() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetProperty.cs:line 20 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Mendix.Modeler.WebUI.Forms.Actions.IActionContainer.GetActionConfig(ClientAction clientAction) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 683 at Mendix.Modeler.WebUI.Forms.Actions.DoNothingClientAction.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Actions\DoNothingClientAction.cs:line 16 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 227 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetObject.<>c__DisplayClass14_0.<Check>b__0(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetObject.cs:line 33 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 337 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetObject.<>c__DisplayClass14_0.<Check>b__0(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetObject.cs:line 33 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.CustomWidget.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\CustomWidget.cs:line 234 at Mendix.Modeler.WebUI.Forms.Widgets.EntityWidgets.DataViews.DataView.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\EntityWidgets\DataViews\DataView.cs:line 76 at Mendix.Modeler.WebUI.Forms.Widgets.FormCalls.LayoutCallArgument.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\FormCalls\LayoutCallArgument.cs:line 28 at Mendix.Modeler.WebUI.Forms.Documents.Layouts.LayoutCall.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Documents\Layouts\LayoutCall.cs:line 36 at Mendix.Modeler.WebUI.Forms.Documents.Pages.Page.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Documents\Pages\Page.cs:line 94 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.Common.ResolveCache.TrackResolves(Action code) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\ResolveCache.cs:line 67 at Mendix.Modeler.Projects.Checks.DocumentCheck.CheckDocument(IDocument document, IUsages usages) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\DocumentCheck.cs:line 45 at Mendix.Modeler.Projects.Checks.DocumentCheck.Check(IProject project, ProjectChanges changes, IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\DocumentCheck.cs:line 30 at Mendix.Modeler.Projects.Checks.ProjectChecker.<>c__DisplayClass5_0.<Check>b__0(ProjectChanges changes) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ProjectChecker.cs:line 54 at Mendix.Modeler.Projects.Checks.ChangedDocumentTracker.TryProcessChangesSync(Action`1 changeProcessor) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ChangedDocumentTracker.cs:line 35 at Mendix.Modeler.Projects.Checks.ProjectChecker.Check(IProject project) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ProjectChecker.cs:line 37 at Mendix.Modeler.Common.BackgroundCheckRunner.Check(IProject project) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 103 at Mendix.Modeler.Common.BackgroundCheckRunner.<>c__DisplayClass5_0.<StartChecking>b__0() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 46 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Mendix.Modeler.Common.BackgroundCheckRunner.<Start>d__4.MoveNext() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 30 --- End of inner exception stack trace --- ---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object. at Mendix.Modeler.WebUI.JSEngine.Manager.JsFunctionCache.JsFunctionLruCache`1.TryGet(IList`1 parameters, Result`1& result) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\JsFunctionCache\JsFunctionLruCache.cs:line 20 at Mendix.Modeler.WebUI.JSEngine.Manager.JsFunctionCache.CachedJsFunction`1.GetResult(WidgetObject widgetObject, JsParameter[] additionalArgs) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\JsFunctionCache\CachedJsFunction.cs:line 30 at Mendix.Modeler.WebUI.JSEngine.Manager.WidgetJsExtensionManager.ComputePropertiesView(CustomWidget customWidget, StudioType studioType) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\WidgetJsExtensionManager.cs:line 129 at Mendix.Modeler.WebUI.JSEngine.Manager.WidgetJsExtensionManager.ComputeProperties(WidgetObject element) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI.JSEngine\Manager\WidgetJsExtensionManager.cs:line 81 at Mendix.Modeler.WebUI.WidgetPackages.CustomWidgetExtensionHelpers.GetPropertyView(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\WidgetPackages\CustomWidgetExtensionHelpers.cs:line 19 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetProperty.GetCaption() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetProperty.cs:line 20 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Mendix.Modeler.WebUI.Forms.Actions.IActionContainer.GetActionConfig(ClientAction clientAction) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 683 at Mendix.Modeler.WebUI.Forms.Actions.DoNothingClientAction.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Actions\DoNothingClientAction.cs:line 16 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 227 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetObject.<>c__DisplayClass14_0.<Check>b__0(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetObject.cs:line 33 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetValue.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetValue.cs:line 337 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.WidgetObject.<>c__DisplayClass14_0.<Check>b__0(WidgetProperty property) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\WidgetObject.cs:line 33 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.WebUI.Forms.Widgets.CustomWidgets.CustomWidget.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\CustomWidgets\CustomWidget.cs:line 234 at Mendix.Modeler.WebUI.Forms.Widgets.EntityWidgets.DataViews.DataView.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\EntityWidgets\DataViews\DataView.cs:line 76 at Mendix.Modeler.WebUI.Forms.Widgets.FormCalls.LayoutCallArgument.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Widgets\FormCalls\LayoutCallArgument.cs:line 28 at Mendix.Modeler.WebUI.Forms.Documents.Layouts.LayoutCall.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Documents\Layouts\LayoutCall.cs:line 36 at Mendix.Modeler.WebUI.Forms.Documents.Pages.Page.Check(IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.WebUI\Forms\Documents\Pages\Page.cs:line 94 at Mendix.Modeler.Utility.EnumerableUtil.ForEach[T](IEnumerable`1 source, Action`1 action) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\EnumerableUtil.cs:line 149 at Mendix.Modeler.Common.ResolveCache.TrackResolves(Action code) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\ResolveCache.cs:line 67 at Mendix.Modeler.Projects.Checks.DocumentCheck.CheckDocument(IDocument document, IUsages usages) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\DocumentCheck.cs:line 45 at Mendix.Modeler.Projects.Checks.DocumentCheck.Check(IProject project, ProjectChanges changes, IProblems problems) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\DocumentCheck.cs:line 30 at Mendix.Modeler.Projects.Checks.ProjectChecker.<>c__DisplayClass5_0.<Check>b__0(ProjectChanges changes) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ProjectChecker.cs:line 54 at Mendix.Modeler.Projects.Checks.ChangedDocumentTracker.TryProcessChangesSync(Action`1 changeProcessor) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ChangedDocumentTracker.cs:line 35 at Mendix.Modeler.Projects.Checks.ProjectChecker.Check(IProject project) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Projects\Checks\ProjectChecker.cs:line 37 at Mendix.Modeler.Common.BackgroundCheckRunner.Check(IProject project) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 103 at Mendix.Modeler.Common.BackgroundCheckRunner.<>c__DisplayClass5_0.<StartChecking>b__0() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 46 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Mendix.Modeler.Common.BackgroundCheckRunner.<Start>d__4.MoveNext() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Core\Common\Problems\BackgroundCheckRunner.cs:line 30<---