Aliasing on normal map

scraffcoff

Found those lines on normal map where UV islands connected

I can't paint on them or cover up

problematic UV's circled in red

this one is another UV island, but have the same problem

those lines also visibile in UE4

Neox

where do you bake these?

as a first measure besides that i would start straightening UV islands, straight pixels just cause less artifacts in general.

also trying to paint over seams of a tangentspace normalmap in diffuse mode is generally not a good idea. if you want to paint over seams of a normalmap, use a worldspace and convert it to tangentspace afterwards.

killnpc

increase or change your padding for the bakes. it looks like the texture is riding the edge too closely. this will become worse when the texture is downrezed. may want to pad the uvs as well, they're riding a little close.