I've tried to find the answer to this myself, but I've looked all over and can't seem to find a solution.
My issue is I get noisey edges when rendering Shadow Passes in the Render Layer system. I've attached a screenshot of my scene showing the issue, as well as my settings.
I've played with every level of samples, specular depth, ray epsilon, caustic blur, GI clamp, and coherent ratio. Nothing gets rid of them. I've done the trick where I fill the scene with a ton of even light and than just reduce the exposure to my desired lighting, but they still appear. Enabling "Only Side Effects" seems to get rid of them, but then it shows shadows behind the objects that I do not want to see. Also it adds weird "scratch marks" in the shadows on the bottom of objects. Also I have no idea wtf this setting is meant for, so I'm hesitant to use it.
Anyone got a clue? Thanks!