On Friday a PC died in the D&D game. Several player errors were made in handling the fight that could've kept the player alive. However, in reviewing how the fight played out and mechanics involved I realized something else: GM error was the biggest reason.
The monster the PCs were fighting had an ability to hide in Dim Lighting. However, 3 of the PCs have the ability to see in Dim Light as if Bright Light, meaning to them the creature couldn't hide. The shadows it was able to camouflage itself in simply didn't exist for them, so they'd just see it hanging out. However, that wasn't something I realized or considered in the moment.
This is different from a player forgetting to use a mechanic, or not realizing/employing an ability properly. This was me, as the GM, restricting actions and artificially inflating the difficulty of the encounter.
So how did we handle it?
First Step: Realize and Verify The Problem
The first thing you need to do is realize where the problem is, and verify that the problem had an impact. For example, during the session I didn't let an action trigger until after the death happened. This was in error. However, said action would not have stopped the monster so it isn't really a problem. On the other hand, ruling that the monster couldn't be seen was both in error and did impact things in a significant manner. It effectively robbed the PCs of 2-3 actions that could, and would have been used to attack. If only one of those attacks hit, the dead PC would have been alive.
So I know for a fact, GM error killed this PC.
Second Step: Discuss With Chief Victim
After knowing I have a problem, I talk to the person most wronged by the error. In this case, the player whose character died. I do this because as the biggest loser from the action they deserve to both hear from me directly and first about the error, as well as to be involved in what we're doing to fix things.
I try to have options already in mind for this. For particularly egregious harm - such as the death of a character - I am willing to rewind the game to fix it, or to find the path of least altering that brings the PC back. Either way, I apologize and it is made a note of to ensure the error doesn't happen again.
Third Step: Present to the Group
After I've talked with the chief victim, I bring it up to the group. They also deserve to know what happened and what is being done. If the impacted player and I didn't lock things down - or if the lock down involves changing the session - this is presented to the group to give their opinions on and be heard. It is their game too, after all.
I also spell out here exactly what the mechanics in play were, how it was ruled, and what the correct ruling was. I do that so everyone knows the way things are supposed to go. That way they can help keep things smooth in the event of a future error.
Fourth Step: Put Plan Into Action
Finally, you put the plan into action, and then keep running as normal.
Final Word: Don't Be Embarrassed
There is nothing to be embarrassed about with a ruling error or GM error. You're only human. Mistakes happen. Own it, learn from it, and move on. You wouldn't expect a player to feel shame because in the heat of the moment they forgot a random character mechanic right? And that is all the player is responsible for. You're balancing all the rules and monster stats and mechanics.
Mistakes happen. They're how you learn.