Operating system: Windows 10, 1803
Graphics card: GTX 1080 TI
Worked: (optional) Few weeks back I didn't notice this issue.
Short description of error
Material turns bright white when using a boolean mesh that is not UV unwrappend and that material is something plugged in the Normal socket.
Exact steps for others to reproduce the error
a) Place a default cube, unwrap it.
b) Give it a material: principled shader with a normal map (and texture) plugged in the normal socket.
c) Add another default cube but switch OFF the option to unwrap it.
d) Give the first default cube a boolean modifier and in the modifier give in the second cube that is not UV unwrapped.
e) The material turn bright white
f) You get the material back when; 1) unwrap the second cube. 2) or unplug the normal map from the normal socket