Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: Intel(R) HD Graphics 4000 Intel 4.0.0 - Build 10.18.10.5069
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-20 14:27, hash: rB26bd5ebd42e3
Short description of error
Principled BSDF Shader produces a the usual pink material regardless of settings. The preview window of the materials shows a pink plain rather than the usual checkered plain that sits under the material.
Exact steps for others to reproduce the error
Not sure if its just my hardware or just a random bug, but this was a fresh install of blender 2.81. I just did a re-download 2.81 and repair to see if that helped; nope. I did update the Intel HD 4000 driver to most recent, and i was warned it may cause problems. Still get it even with the most to date driver. I usually operate all of blender off the NVidia GTX 1060 GPU and through CUDA. Works fine in Cycles, and is only apparent in Eevee.
...And while grabbing screenshots I just solved some of it. I did a factory reset to blender, switched between eevee to cycles, then back to eevee, and only once i got it switched to render mode did it update the shader, but not the preview. So maybe one less bug? Still going to send pics to help anyone else.