Seams visible in final render

I am seeing seems in my final render.

I am doing a draft render for the moment…

For the first issue you can increase the lightmap resolution just for the sofa using the Custom lightmap resolution setting in the Objects tab.

For the second one: the emissive material is shining not only downwards, but also upwards - to the ceiling, and due to the limited lightmap resolution the illumination on the ceiling is leaking outside the light fixture. Is the light fixture closed on the top (from the ceiling side)?

Wojtek, thanks… I will check both recommendation.