How to avoid Halo Lighting ? - Help!

Hi All
Whenever I make any light fixture like seen in the sketch below, regardless of whether I use an emitter material, a point light or a spotlight as a light source, this light fixture always causes Halo Lighting on the ceiling or at the wall around the light fixture . But since the light fixture is made like seen in the sketch, this should not happen.
What am I doing wrong ?!? - please help!


Make sure that you checked the Shadow box in the options of the light, or that your light is not too close from the ceiling.

Maybe could you share a example file with us ?

Best regards

Thank you - I just sent you a skp file via email