Cycles high angle face artefact I have a sun lamp at 90 degrees to a curved mesh. In Eevee, the shadow renders as smooth. However, in Cycles, I get these black artefacts - entire faces on the shadow edge are black.
How do I fix this? I've played around with the mesh normals, material settings, etc. No luck.

Update
I fixed this with Subsurf modifier. Is there a better way?
Shadow Terminator Offset
you can find this setting in
Properties ‣ Object Properties ‣ Shading
increase it to 0.15 which is really enough
Note: this is a new feature came in blender 2.90 so you need to update blender to some newer version



Note
This property artificially alters the scene’s lighting and is not
energy conserving and consequently not physically accurate.

Got from the blender Manual: https://docs.blender.org/manual/en/2.90/render/cycles/object_settings/object_data.html#shading