Crash On Opening Project (4.7.6)

Hey all

Project was working fine yesterday. This morning it refuses to load and crashes upon opening

Extra details:

The loading % gets up to 95, then just sits there for about 30 seconds before it crashes with the crash reporter.

All other projects work fine

I’m using the launcher to open the project

I tried to open a copy with the source version of the engine from github last night. But it froze at 9% so I killed it with the task manager. I’m betting that this is the culprit but I have no idea why.

Crash report data:


MachineId:CBCA38B141287FA1C76D1C9DB8BA9EBE
EpicAccountId:72ff4318d7fc4261993270f6146dc4cd

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 + 109229 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:3933]
UE4Editor_CoreUObject!ULinkerLoad::Detach() + 27 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp:3849]
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::LoadDefaultMapAtStartup() + 216 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\filehelpers.cpp:3070]
UE4Editor_UnrealEd!FUnrealEdMisc::OnInit() + 2263 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\unrealedmisc.cpp:299]
UE4Editor_UnrealEd!EditorInit() + 3254 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\unrealed.cpp:86]
UE4Editor!GuardedMain() + 926 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launch.cpp:133]
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]


Ok so I’ve managed to find a workaround.

I went into the DefaultEngine.ini file in the project folder and removed the EditorStartupMap value. This finally allowed me to get into the editor without any crashing.

I tried to open the .umap that I was using prior, but it crashed. So I guess it’s just corrupted.

Luckily I have an autosave .umap file from the day before, not much lost in terms of progress.

Hopefully this helps for anyone who has the same issue in the future.