This was a huge problem for me in this project, i worked on the uv maps for the assets for ages trying to perfect the seams getting them all sewn together neatly so they would look very clean but every time i tried to bake the models details the models always came out with the hard edges looking weirdly shaded and the model coming out with various shading errors.
I had been stuck on this error up until 2 days before hand in but it turns out my issue was extremely simple and that just made it even more frustrating when i figured it out.
My set up for baking was to soften the edges of the model in maya then harden the uv edges, after that i would export the lp mesh and its cage. Then i would export the hp mesh from zbrush and bring it into xnormal for baking.
The majority of these came out clean but i did run into an issue where there would be small black triangles on the models. However these were easily corrected by bringing the normals into photoshop and paint over them. This happened on my sword here is how it looks before and after, you can see the small triangles on the handguard of the sword.
Here are a few of the normal maps and the models with them.