Unreal Engine scene crashes on launch at 87% every time

Hi guys I ran into a huge problem with my scene. For some reason it just crashes at 87% every time I try to load it. I’m not sure what caused it as I haven’t done anything outside of putting meshes and materials in. Here’s the report data :

MachineId:1C02BC2C4EF7CACD6EB447BC94714092
EpicAccountId:bfb019c6fc4b46c5b67232a2baec530a

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

Assertion failed: FCompression::UncompressMemory( Flags, Dest, Chunk.UncompressedSize, CompressedBuffer, Chunk.CompressedSize, (Padding > 0) ? true : false ) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.7\Engine\Source\Runtime\Core\Pri

KERNELBASE + 35740 bytes
UE4Editor_Core!FOutputDeviceWindowsError::Serialize() + 292 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:95]
UE4Editor_Core!FOutputDevice::Logf__VA() + 248 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\misc\outputdevice.cpp:144]
UE4Editor_Core!FDebug::AssertFailed() + 1079 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\misc\outputdevice.cpp:224]
UE4Editor_Core!FArchive::SerializeCompressed() + 961 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\serialization\archive.cpp:394]
UE4Editor_CoreUObject!FUntypedBulkData::SerializeBulkData() + 172 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\serialization\bulkdata.cpp:1009]
UE4Editor_CoreUObject!FUntypedBulkData::LoadDataIntoMemory() + 123 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\serialization\bulkdata.cpp:1113]
UE4Editor_CoreUObject!FUntypedBulkData::DetachFromArchive() + 147 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\serialization\bulkdata.cpp:893]
UE4Editor_CoreUObject!ULinkerLoad::DetachAllBulkData() + 233 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp:3928]
UE4Editor_CoreUObject!ULinkerLoad::Detach() + 27 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp:3844]
UE4Editor_CoreUObject!ResetLoaders() + 1108 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\linker.cpp:383]
UE4Editor_CoreUObject!UObject::Rename() + 842 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\obj.cpp:130]
UE4Editor_Engine!AActor::Rename() + 77 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\actor.cpp:614]
UE4Editor_Engine!UNavigationSystem::CreateNavigationDataInstance() + 494 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:2917]
UE4Editor_Engine!UNavigationSystem::UpdateAbstractNavData() + 701 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:297]
UE4Editor_Engine!UNavigationSystem::DoInitialSetup() + 27 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:268]
UE4Editor_Engine!UNavigationSystem::OnWorldInitDone() + 61 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:460]
UE4Editor_Engine!UNavigationSystem::InitializeForWorld() + 275 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:1983]
UE4Editor_UnrealEd!UEditorEngine::Map_Load() + 8712 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\editorserver.cpp:2382]
UE4Editor_UnrealEd!UEditorEngine::HandleMapCommand() + 349 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\editorserver.cpp:5680]
UE4Editor_UnrealEd!UEditorEngine::Exec() + 797 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\editorserver.cpp:5180]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() + 273 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\unrealedsrv.cpp:742]
UE4Editor_UnrealEd!FEditorFileUtils::LoadMap() + 789 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\filehelpers.cpp:1910]
UE4Editor_UnrealEd!FEditorFileUtils::LoadMap'::8’::FLocal::HandleLevelsChosen() + 222 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\filehelpers.cpp:1779]
UE4Editor_UnrealEd!TBaseStaticDelegateInstance const & ptr64)>::ExecuteIfSafe() + 13 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:921]
UE4Editor_UnrealEd!FEditorFileUtils::OpenLevelPickingDialog'::2’::FLocal::OnLevelsSelected() + 485 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\filehelpers.cpp:1570]
UE4Editor_UnrealEd!TBaseStaticDelegateInstance const & ptr64),TBaseDelegate const & ptr64> >::ExecuteIfSafe() + 50 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:922]
UE4Editor_ContentBrowser!SAssetDialog::ChooseAssetsForOpen() + 141 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\editor\contentbrowser\private\sassetdialog.cpp:486]
UE4Editor_ContentBrowser!SAssetDialog::OnAssetsActivated() + 70 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\editor\contentbrowser\private\sassetdialog.cpp:403]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetDialog,0,TTypeWrapper cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() + 87 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\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() + 71 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!SAssetPicker::HandleAssetsActivated() + 167 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\editor\contentbrowser\private\sassetpicker.cpp:393]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetPicker,0,TTypeWrapper cdecl(TArray const & ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() + 87 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\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() + 71 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!SAssetView::OnListMouseButtonDoubleClick() + 823 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\editor\contentbrowser\private\sassetview.cpp:3207]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper cdecl(TSharedPtr)>::Execute() + 97 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,void cdecl(TSharedPtr)>::ExecuteIfSafe() + 90 bytes [d:\buildfarm\buildmachine++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!TBaseDelegate >::ExecuteIfBound() + 86 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:518]
UE4Editor_ContentBrowser!SListView >::Private_OnItemDoubleClicked() + 63 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\public\widgets\views\slistview.h:693]
UE4Editor_ContentBrowser!STableRow >::OnMouseButtonDoubleClick() + 223 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\public\widgets\views\stablerow.h:252]
UE4Editor_Slate!::operator()() + 30 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3918]
UE4Editor_Slate!FEventRouter::Route >() + 189 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:202]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonDoubleClickEvent() + 471 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3919]
UE4Editor_Slate!FSlateApplication::OnMouseDoubleClick() + 315 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3900]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() + 3176 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsapplication.cpp:1315]
UE4Editor_Core!FWindowsApplication::DeferMessage() + 318 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsapplication.cpp:1669]
UE4Editor_Core!FWindowsApplication::ProcessMessage() + 4016 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsapplication.cpp:742]
UE4Editor_Core!FWindowsApplication::AppWndProc() + 114 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsapplication.cpp:604]
user32 + 9485 bytes
user32 + 9063 bytes
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() + 118 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:774]
UE4Editor!FEngineLoop::Tick() + 3737 bytes [d:\buildfarm\buildmachine
++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launchengineloop.cpp:2233]
UE4Editor!GuardedMain() + 1404 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]

Hi photonarbiter,

Does this occur in a clean project with no additional content or is it limited to one project? Additionally, how many meshes/materials do you have in your level? Are you using static or dynamic lighting? Finally, can you post your crash logs (\Unreal Projects\PROJECTNAME\saved\logs) and your dxdiag here so I can take a look?

Hi photonarbiter,

We have not heard from you in several days. I am marking this as answered for tracking purposes. If you are still experiencing this error, please comment here with the requested information.