Fatal error:

Every now and again (1 in every ~10) when I press play (not for the first times in an editor session) I get this fatal error followed by a crash dump of the editor.

I’ve checked all the pointer assignments and protected them. It started about 4-5 videos ago. If I start the editor and press play it almost never crashes and in standalone mode outside of the editor, it rarely crashes.

It seems like something is being called before it is properly initialised.

Fatal error: [File:D:/Build/++UE4/Sync/Engine/Source/Runtime/Core/Private/Windows/WindowsPlatformMisc.cpp] [Line: 475] 
Pure virtual function being called

0x00007ffcfcb64b89 KERNELBASE.dll!UnknownFunction []
0x00007ffc7b41d066 UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7b4207a8 UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7b12e8cd UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7b437360 UE4Editor-Core.dll!UnknownFunction []
0x00007ffcdff76bf4 VCRUNTIME140.dll!UnknownFunction []
0x00007ffc7a7704b4 UE4Editor-CoreUObject.dll!UnknownFunction []
0x00007ffc7a9b635b UE4Editor-CoreUObject.dll!UnknownFunction []
0x00007ffc7a976c61 UE4Editor-CoreUObject.dll!UnknownFunction []
0x00007ffc7a97fb18 UE4Editor-CoreUObject.dll!UnknownFunction []
0x00007ffc7aeddf05 UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7aedf160 UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7aee6495 UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7b43898b UE4Editor-Core.dll!UnknownFunction []
0x00007ffc7b431620 UE4Editor-Core.dll!UnknownFunction []
0x00007ffcfe157034 KERNEL32.DLL!UnknownFunction []
0x00007ffcfee82651 ntdll.dll!UnknownFunction []

Crash in runnable thread TaskGraphThreadNP 4

I saw this too! In fact I keep getting it - it pops up about calling a pure virtual, hangs and crashes. I find it only seems to happen if I leave the machine for a few hours/overnight and often happens the next day.

It’s usually when I flick between Join and Host within the editor which makes me think it’s an issue with the Interface Abstract class/Interface that was created since it’s the only place with pure virtual functions. I was thinking of making the methods just virtuals - instead of = 0, do { } and this might solve the issue. Worth a try and while things may not work as intended, it might stop crashing.