Blender 2.8 material turn into black stroke material

my normal cycles material always turn into this black stroke material ,any one know how to reverse back to normal one??? so strange

You don’t have node output or nothing is connected to output node in nodes for that material.

it has a stroke (line) tab. I dont know how to turn it back to normal cycles material. I dont know what button I pushed… this is annoying

The image shows the nodes for your world settings, not the material nodes.

for solution ,go to the link below