How to setup material node to change the shadow colour with using the light path node?
Mix your material with a colored transparent material using Is Shadow Ray as the mix factor.
Your setup is ok, and your shadows do not look dark to me.
(you have to apply this shader to the cube in my example, not to the ground)
But if you want to change shadow colors, doing it in the material is not accurate. My advice is to add other lamps, or increase world color with higher value. It will be more natural.
You have it on the wrong object. In path tracing shadows are the product of the object casting them, not of the object receiving them.
Ok thanks.I put it on the wrong object. Adding another lamp or adjusting the world strength will be the option or else i will have to change material one by one.