What is the likely cause of a light not turning on when a player enters a doorway?

When a player enters a doorway, a common event is to trigger actions such as turning on a light. For this to occur, the doorway's collider must be set up correctly. If the doorway's collider is not marked as a trigger, it will not generate the necessary collision events when the player enters, preventing any script designed to respond to this event from executing.

Marking a collider as a trigger allows it to detect overlaps with other colliders, which is essential for handling events like lighting changes when the player crosses through the doorway. If this is not configured correctly, the expected behavior—such as turning the light on—will not happen because the system does not recognize that the player has entered the area that should trigger that action. Proper setup of trigger colliders is fundamental in Unity for enabling interactions based on player movements.