This is a common crash that has occurred since at least 4.16.
The callstack is nearly identical to
UE-48997, which appears to be fixed in 4.18; and UE-51783, which has not. The difference is that this callstack specifically references UMaterialFunctionThumbnailRenderer::Draw.
- I was in the materials editor. I had bit mask selected through the Left Click Search menu. To select the Bit Mask, I went to press "Enter"; on the numberpad, but accidently hit either the "3" key, or the "."
- I cloned out a speed tree color variation node in a material.
- Died when i tried to dublica lerp with ctrl-W. I am running with 4gb ram, might be why. Google chrome running in the background taking up 1gig ram
1638 AWorldSettings* ULevel::GetWorldSettings(bool bChecked) const
1640 if (bChecked)
1642 ***** checkf( WorldSettings != nullptr, *GetPathName() );
1644 return WorldSettings;