Many questions have been asked about this, and I tried all their answers, and nothing for me has gotten rid of this error.
I baked a normals map for my retopology character. I made tons of textures, and shaders, and now that I'm ready to render in Cycles, an inverted-like shade has become visible at the seams, like an inverted checkered board.
It still shows in the final render as well, and Flat/Smooth shading won't change anything either.
How is this issue caused, and how do I fix it?
A view of the normal map as a texture, without any normal map displacement.
EDIT 3: I changed the Normal Map Node's Tangent Space to Object and World, as well as the others, and it fixed the odd shading, but it left lines where the seams are. As well as the lines, it completely messed up my normal and displacement maps on the front. The best overall look (except these awful shading lines/boxes) is the Tangent Space.
EDIT 4: Normal maps/settings Old, as in the one used in all other pictures, new as in just out of the oven.