Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.15
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
Black artifacts on edges of geometry while using adaptive subdivision. I was trying to duplicate my workflow from other 3d software. Extruding geometry from 2d curves creates extra edges on the model. And extra edges create weird shadows on displacement.
Exact steps for others to reproduce the error
Import curve from dxf file. Use extrude Object Data > Geometry. Fill mode: Both. Use subdivision and displacement.