4.12.5 My Map wont open

Please help, this is the second map that 4.12.5 has crashed and wont open for me.
This is meant to be my main assignment for uni and unreal keeps getting to a certain stage and crashes.
What is the issue?

This is the crash report

MachineId:BAE449C5491D4D0799FE34A45C6874C4
EpicAccountId:e425b2eb4ab94e29aa36688d57772efd

Fatal error: [File:D:\Build++UE4+Release-4.12+Compile\Sync\Engine\Source\Runtime\Foliage\Private\FoliageInstanceBase.cpp] [Line: 90]
Instance base cache - integrity verification(3): Counter: 13 Size: 12, InvSize: 7 (L:1 S:0 T:0)

UE4Editor_Core!FDebug::AssertFailed() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:440]
UE4Editor_Foliage!operator<<() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\foliage\private\foliageinstancebase.cpp:93]
UE4Editor_Foliage!AInstancedFoliageActor::Serialize() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\foliage\private\instancedfoliage.cpp:2247]
UE4Editor_CoreUObject!FLinkerLoad::Preload() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp:3293]
UE4Editor_CoreUObject!EndLoad() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1411]
UE4Editor_CoreUObject!LoadPackageInternal() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1171]
UE4Editor_CoreUObject!LoadPackageInternal() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1286]
UE4Editor_CoreUObject!ResolveName() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:696]
UE4Editor_CoreUObject!StaticLoadObjectInternal() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:783]
UE4Editor_CoreUObject!StaticLoadObject() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:853]
UE4Editor_ContentBrowser!ContentBrowserUtils::LoadAssetsIfNeeded() [d:\build++ue4+release-4.12+compile\sync\engine\source\editor\contentbrowser\private\contentbrowserutils.cpp:335]
UE4Editor_ContentBrowser!SAssetView::CanOpenContextMenu() [d:\build++ue4+release-4.12+compile\sync\engine\source\editor\contentbrowser\private\sassetview.cpp:3511]
UE4Editor_ContentBrowser!SAssetView::OnGetContextMenuContent() [d:\build++ue4+release-4.12+compile\sync\engine\source\editor\contentbrowser\private\sassetview.cpp:3438]
UE4Editor_ContentBrowser!TMemberFunctionCaller (__cdecl SAssetView::)(void) __ptr64>::operator()<>() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface_variadics.h:161]
UE4Editor_ContentBrowser!TTupleImpl >::ApplyAfter_ExplicitReturnType,TMemberFunctionCaller (__cdecl SAssetView::
)(void) __ptr64> >() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\tuple.h:128]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,TSharedPtr __cdecl(void)>::Execute() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:321]
UE4Editor_Slate!TBaseDelegate >::Execute() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:521]
UE4Editor_Slate!STableViewBase::OnRightMouseButtonUp() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\widgets\views\stableviewbase.cpp:778]
UE4Editor_ContentBrowser!SListView >::Private_OnItemRightClicked() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\public\widgets\views\slistview.h:683]
UE4Editor_ContentBrowser!STableRow >::OnMouseButtonUp() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\public\widgets\views\stablerow.h:477]
UE4Editor_Slate!::operator()() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4630]
UE4Editor_Slate!FEventRouter::Route >() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4621]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5041]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5021]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1510]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1850]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:745]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:667]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:903]
UE4Editor!FEngineLoop::Tick() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2729]
UE4Editor!GuardedMain() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launch.cpp:148]
UE4Editor!GuardedMainWrapper() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll

Hey Lupus_Amor,

This is a known issue that was resolved in 4.13. Here is a link to the issue on the public tracker:

Have a great day