UE4.9.2 Crash when opening project - Assertion failed

This is the following error message I get when trying to open up my project. I first got it today on 4.9.0, decided to upgrade incase it would fix the problem. So far I have tried to remove all DCC (both within the installation folders aswell as under my windows user), opening up the project with a default map and then open the actual level giving me problems but there problem still persist. I am able to open other projects fine however this one is giving me a major headache. Any solution to this would be greatly helpful!

MachineId:DF98639F4CDEEF4E2FCB4295C530B96A
EpicAccountId:ca957f2a612740e09b9f0c6e068f7e25

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

"Assertion failed: !Cache.InstanceBaseInvMap.Contains(BaseInfo.BasePtr) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.9\Engine\Source\Runtime\Foliage\Private\FoliageInstanc

UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\misc\outputdevice.cpp:354]
UE4Editor_Foliage!FFoliageInstanceBaseCache::CompactInstanceBaseCache() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\foliage\private\foliageinstancebase.cpp:241]
UE4Editor_Foliage!AInstancedFoliageActor::PostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\foliage\private\instancedfoliage.cpp:2354]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\obj.cpp:723]
UE4Editor_CoreUObject!UObject::PostLoadSubobjects() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\obj.cpp:744]
UE4Editor_CoreUObject!UObject::ConditionalPostLoadSubobjects() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\obj.cpp:812]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\obj.cpp:720]
UE4Editor_CoreUObject!EndLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1285]
UE4Editor_CoreUObject!LoadPackageInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1041]
UE4Editor_UnrealEd!UEditorEngine::Map_Load() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:2335]
UE4Editor_UnrealEd!UEditorEngine::HandleMapCommand() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:5823]
UE4Editor_UnrealEd!UEditorEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:5317]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\unrealedsrv.cpp:743]
UE4Editor_UnrealEd!FEditorFileUtils::LoadMap() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\filehelpers.cpp:2014]
UE4Editor_UnrealEd!FEditorFileUtils::LoadMap'::8’::FLocal::HandleLevelsChosen() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\filehelpers.cpp:1880]
UE4Editor_UnrealEd!TBaseStaticDelegateInstance const & ptr64)>::ExecuteIfSafe() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:921]
UE4Editor_UnrealEd!FEditorFileUtils::OpenLevelPickingDialog'::2’::FLocal::OnLevelsSelected() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\filehelpers.cpp:1661]
UE4Editor_UnrealEd!TBaseStaticDelegateInstance const & ptr64),TBaseDelegate const & ptr64> >::ExecuteIfSafe() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:922]
UE4Editor_ContentBrowser!SAssetDialog::ChooseAssetsForOpen() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\sassetdialog.cpp:484]
UE4Editor_ContentBrowser!SAssetDialog::OnAssetsActivated() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\sassetdialog.cpp:401]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetDialog,0,TTypeWrapper cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetDialog,0,void cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::ExecuteIfSafe() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!SAssetPicker::HandleAssetsActivated() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\sassetpicker.cpp:401]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetPicker,0,TTypeWrapper cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetPicker,0,void cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::ExecuteIfSafe() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!SAssetView::OnListMouseButtonDoubleClick() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\sassetview.cpp:3287]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper cdecl(TSharedPtr)>::Execute() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,void cdecl(TSharedPtr)>::ExecuteIfSafe() [d:\buildfarm\buildmachine++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!TBaseDelegate >::ExecuteIfBound() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:482]
UE4Editor_ContentBrowser!SListView >::Private_OnItemDoubleClicked() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\public\widgets\views\slistview.h:689]
UE4Editor_ContentBrowser!STableRow >::OnMouseButtonDoubleClick() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\public\widgets\views\stablerow.h:261]
UE4Editor_Slate!::operator()() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4606]
UE4Editor_Slate!FEventRouter::Route >() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:214]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonDoubleClickEvent() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4607]
UE4Editor_Slate!FSlateApplication::OnMouseDoubleClick() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4587]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:1345]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:1708]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:706]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:628]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:884]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine
++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launchengineloop.cpp:2392]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Hi meepie -

Can you confirm that you have actually submitted your Crash via the Epic Crash Reporter? If you do not send the crash we will not be able to track down the issue successfully. That being said I believe that I have found another user with the same crash call stack.

Based on that call stack and what I can get from the call stack posted above. The issue has something to do with your Foliage in the level. Can you provide any and all information regarding your foliage and landscape setup as it is in the level causing you the issues?

Thank You

Eric Ketchum

Hi, sorry for the delay.
I had to go back a version of the scene to get it to work, however now the same issue has started to appear again, sometimes affecting multiple file versions within the project.
As far as I have understood from the crash logs it has to do with Foliage like you said. I’m having quite alot of foliage within the scene, it’s not a huge landscape by any means but it’s quite dense on foliage yet I’m not able to reach the amount I need.
Can this be related to reach some upper limit on amount of foliage? What is odd is how it makes it impossible to open not just one but several files.
I’m having about 18-19.000 foliage instances, most of this is small Clover on the ground aswell as some trees bushes, ferns etc.

Not sure if this is related at all, but I noticed that the first time this happend was after the launcher had done an auto update and required a restart, yesterday this happend again and also after a launcher update (scene was open during both times during the launcher update) although I have a hard time seeing how it could be related to this, but an interesting coincidence.

Thanks for any further help!

So I setup a test map with a grass mesh at 575K foliages meshes painted on a default landscape and was so far unable to reproduce the crash. Is it possible for you to share your project with us? If you would like to keep it confidential you can link me a download site via the Engine Forums Private Message System.

Thank You

Eric Ketchum

Hi meepie,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.

Thank you.

Eric Ketchum