Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce RTX 2070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.67
Broken: version: 2.80 (sub 51), branch: blender2.7, commit date: 2019-03-24 00:06, hash: rB79f67acccb36
Short description of error
Glossy black material generates a lot of black pixels NaN in final render. The more render samples the more NaN pixels. In the viewport is less noticeable because their are less render samples. Turn off SSR and NaN pixels are gone.
See attach image:
Exact steps for others to reproduce the error
Load attach blender file "Glossy SSR_NAN_Bug.blend".
Render F12 notice all the black NAN pixels. Turn off SSR and all the black NaN pixels are gone.