One scene I was trying to render but couldn't, ended up being a problem with the size of the shadow maps for one of the lights. It was in the thousands. I reduced it to 256 and then was able to render fine.

It might not be your problem, but it's something worth looking at.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi