How to render an image with holdout material in Cycles 2.8? thats almost litterally the question asked here but these don't seem to be working with 2.80
Can Blender render pngs with the background transparent?

i have PNG, Rgba, 8bit, 15% compression  and the holdout material still renders as black.
You need to enable World background transparency.

It's in Render Tab > Film > Transparent
Check ✔ Transparent and you're done.