Unreal Engine Issues and Bug Tracker (UE-19741)

Description

If the user adds two widgets to a switcher and then tries to drag one out of it the editor will crash

Steps to Reproduce

open Editor
Create a new widget blueprint
Open widget blueprint
Add a Switcher Widget to the designer tab
Add two text widgets to the switcher widget
Click and drag one of the text widgets out of the Switcher widget and drop it onto the canvas panel
Notice that the editor crashes

Expected: The widget would be removed from the switcher widget and would then be placed on the canvas panel
Result: The editor crashes

Callstack

MachineId:E74C21034048BDD873CC6C9A3913CF6C
EpicAccountId:ccbf39de6f9245c0aa23f8e57cc8a566

Unknown exception - code 00000001 (first/second chance not available)

"Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.8\Engine\Source\Runtime\Core\Public\Con

UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\misc\outputdevice.cpp:355]
UE4Editor_Slate!TPanelChildren<SWidgetSwitcher::FSlot>::operator[]() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\public\layout\children.h:264]
UE4Editor_Slate!TPanelChildren<SWidgetSwitcher::FSlot>::GetChildAt() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\public\layout\children.h:224]
UE4Editor_Slate!SWidgetSwitcher::FOneDynamicChild::GetChildAt() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\public\widgets\layout\swidgetswitcher.h:160]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:384]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_SlateCore!SWidget::SlatePrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slatecore\private\widgets\swidget.cpp:389]
UE4Editor_Slate!PrepassWindowAndChildren() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:1064]
UE4Editor_Slate!PrepassWindowAndChildren() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:1072]
UE4Editor_Slate!FSlateApplication::DrawPrepass() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:1110]
UE4Editor_Slate!FSlateApplication::PrivateDrawWindows() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:1149]
UE4Editor_Slate!FSlateApplication::DrawWindows() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:941]
UE4Editor_Slate!FSlateApplication::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:1440]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launchengineloop.cpp:2392]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Community References

Widget Switcher Array Index Crash [Repro]

Crash with UWidgetSwitcher in designer

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Fixed

Component	UE - Editor - UI Systems
Affects Versions	4.8.3
Target Fix	4.10

Fix Commit	2649266
Release Commit	2712981

Created	Aug 6, 2015
Resolved	Aug 10, 2015
Updated	Feb 27, 2017

UE-19741

Switcher widget causes a crash when dragging a widget out of it and on to the canvas panel

Switcher widget causes a crash when dragging a widget out of it and on to the canvas panel

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