When I attempt to open this project, which has never had any problems before, the engine crashes without the level even opening. here is the callstack:
Unknown exception - code 00000001 (first/second chance not available)
Assertion failed: BlueprintObj->GeneratedClass [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.6\Engine\Source\Editor\UnrealEd\Private\Kismet2\Kismet2.cpp] [Line: 542]
Invalid generated class for LockedDoorBlueprint
KERNELBASE + 37901 bytes
UE4Editor_Core + 3092349 bytes
UE4Editor_Core + 1597688 bytes
UE4Editor_Core + 1479058 bytes
UE4Editor_UnrealEd + 10034613 bytes
UE4Editor_Engine + 1970481 bytes
UE4Editor_CoreUObject + 240879 bytes
UE4Editor_CoreUObject + 946774 bytes
UE4Editor_CoreUObject + 1054484 bytes
UE4Editor_CoreUObject + 944791 bytes
UE4Editor_CoreUObject + 947419 bytes
UE4Editor_CoreUObject + 1062891 bytes
UE4Editor_CoreUObject + 1460613 bytes
UE4Editor_CoreUObject + 1193007 bytes
UE4Editor_CoreUObject + 1189666 bytes
UE4Editor_CoreUObject + 1193874 bytes
UE4Editor_CoreUObject + 1189666 bytes
UE4Editor_CoreUObject + 1189156 bytes
UE4Editor_CoreUObject + 976397 bytes
UE4Editor_CoreUObject + 1185872 bytes
UE4Editor_CoreUObject + 951800 bytes
UE4Editor_CoreUObject + 1026078 bytes
UE4Editor_CoreUObject + 1460171 bytes
UE4Editor_UnrealEd + 2768012 bytes
UE4Editor_UnrealEd + 2700861 bytes
UE4Editor_UnrealEd + 2612749 bytes
UE4Editor_UnrealEd + 6316416 bytes
UE4Editor_UnrealEd + 3168772 bytes
UE4Editor_UnrealEd + 3167944 bytes
UE4Editor_UnrealEd + 6555369 bytes
UE4Editor_UnrealEd + 6310846 bytes
UE4Editor!GuardedMain() + 285 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\launch.cpp:123]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]
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