When a guy opens up to you about the death of a loved one, is there a proper way to respond?

The first time it happened, I was shocked because I didn't expect it in a casual conversation.
But then a loved one died and when it happened to me, a part of me would have appreciated it if I was asked about it. Not for the sake of giving condolence or forgetting but to remember the fun times. Even though honestly, it still hurts.

But then it happened with another guy friend and when I tried to be nice and asked about the loved one, it kinda felt like he wanted me to stop and changed the topic. So I think it varies from person to person. But really... how does one know how to react? Or, what even is needed?