Error while switching from Content Browser to Output Log tab in Editor

From time to time I am receiving following error message in log while switching from Content Browser to Output Log tab in Editor (program doesn’t crash):

LogOutputDevice:Warning: === Handled error: ===
Ensure condition failed: TabBeingDraggedPtr.IsValid() [File:D:\Build++UE4+Release-4.12+Compile\Sync\Engine\Source\Runtime\Slate\Private\Framework\Docking\SDockingTabWell.cpp] [Line: 374]
Stack:
UE4Editor-Core.dll!FWindowsPlatformStackWalk::StackWalkAndDump() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsplatformstackwalk.cpp:183]
UE4Editor-Core.dll!FDebug::EnsureFailed() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:327]
UE4Editor-Core.dll!FDebug::OptionallyLogFormattedEnsureMessageReturningFalse() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:451]
UE4Editor-Slate.dll!SDockingTabWell::OnDrop() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\docking\sdockingtabwell.cpp:374]
UE4Editor-Slate.dll!::operator()() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4630]
UE4Editor-Slate.dll!FEventRouter::Route >() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor-Slate.dll!FSlateApplication::RoutePointerUpEvent() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4621]
UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5041]
UE4Editor-Slate.dll!FSlateApplication::OnMouseUp() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5021]
UE4Editor-Core.dll!FWindowsApplication::ProcessDeferredMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1510]
UE4Editor-Core.dll!FWindowsApplication::DeferMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1850]
UE4Editor-Core.dll!FWindowsApplication::ProcessMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:745]
UE4Editor-Core.dll!FWindowsApplication::AppWndProc() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:667]
USER32.dll
USER32.dll
UE4Editor-Core.dll!FWindowsPlatformMisc::PumpMessages() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:903]
UE4Editor.exe!FEngineLoop::Tick() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2729]
UE4Editor.exe!GuardedMain() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launch.cpp:148]
UE4Editor.exe!GuardedMainWrapper() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor.exe!WinMain() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
KERNEL32.DLL
ntdll.dll
ntdll.dll

Hello,

I have a few questions regarding this issue:

  • Does this ensure occur every time you do this?
  • Could you please provide your dxdiag?
  • Does this occur if you test it in a clean project?
  • Does it occur if you test it in 4.13 Preview 3?
  1. Issue occurs quite randomly and I have no idea how to reproduce it but I can say that it happens about one or two times per several hours
  2. My dxdiag
  3. I have nothing related to UI in my project so I think it would happen in a clean one too (but since error appears randomly I don’t want to wait until it happens)

Hey -Pavel-,

Unfortunately, I’ve not been able to see this occurring on my end. It could be something related to the integrated graphics card that you are using. I’d recommend looking into updating the drivers on it if you haven’t already.

If you are able to determine a solid way to reproduce this issue in a clean project, please feel free to respond to that thread. Until we have a way to reproduce the issue, we are limited as far as what action we can take.

Have a great day