Light mass crashed how to fix it?

=== Lightmass crashed: ===
Fatal error: [File:D:\Build++UE4\Sync\Engine\Source\Programs\UnrealLightmass\Private\Lighting\LightingSystem.cpp] [Line: 1356]
Static lighting thread exception:
Fatal error: [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Private\GenericPlatform\GenericPlatformMemory.cpp] [Line: 193]
Ran out of memory allocating 4177936 bytes with alignment 0

0x00007ffffdc850d8 KERNELBASE.dll!UnknownFunction []
0x00007fffe3cb4a10 UnrealLightmass-ApplicationCore.dll!UnknownFunction []
0x00007fffcc1c955c UnrealLightmass-Core.dll!UnknownFunction []
0x00007fffcc15aa4d UnrealLightmass-Core.dll!UnknownFunction []
0x00007fffcc047bb4 UnrealLightmass-Core.dll!UnknownFunction []
0x00007fffcc0b73af UnrealLightmass-Core.dll!UnknownFunction []
0x00007ff67455d177 UnrealLightmass.exe!TArray::ResizeTo() []
0x00007ff6745b9005 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::RadiositySetupTextureMapping() []
0x00007ff6745ba793 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::RadiositySetupThreadLoop() []
0x00007ff6745c0e1b UnrealLightmass.exe!Lightmass::FMappingProcessingThreadRunnable::Run() []
0x00007fffcc39af98 UnrealLightmass-Core.dll!UnknownFunction []
0x00007fffcc395977 UnrealLightmass-Core.dll!UnknownFunction []
0x00007ff800741fe4 KERNEL32.DLL!UnknownFunction []
0x00007ff80178cb31 ntdll.dll!UnknownFunction []

Hi,
did you fix the problem? I have the same problem…
If you have a solution please share it!