Problem with lighting on android mobile

As you can see in the attached image (screenshot of game from mobile), there is is problem in lighting , those primitive cuboids are suppose to be clean green, but I'm getting those black lines.

 

Those are artifacts from your objects going in and out of their own self-shadow. Some common fixes are increasing your shadow bias (and in your case, especially normal bias) on your light, improving shadow quality and moving your shadow cascade splits around to better closely bound your objects (both in edit->projectsettings->quality).

Also it's kind of hard to tell but it looks like your main light might be very close to directly overhead, which would be worst case for the vertical surfaces on your blocks - you could try rotating the light down a little bit so the light rays don't hit those surfaces at such a grazing angle.

 

thank you! It has greatly improved the lighting in my game