Fix: Unity Input System Control Scheme Auto-Switch Broken

Player picks up a controller mid-game. Game keeps reading keyboard. Or vice versa. Auto-Switch is off or the PlayerInput is configured for multiplayer.

The Symptom

Single-player game doesn’t hot-swap between keyboard/mouse and gamepad. UI prompts don’t update. Or attempting to swap by pressing buttons does nothing.

The Fix (Single Player)

PlayerInput Inspector:
  Actions:           PlayerControls (asset)
  Default Scheme:    Keyboard&Mouse
  Auto-Switch:       true          // THIS
  Behavior:          Invoke Unity Events

Listen for swap:

public class PromptUpdater : MonoBehaviour
{
    public PlayerInput playerInput;
    public Image promptImage;
    public Sprite kbIcon, padIcon;

    void OnEnable()  => playerInput.onControlsChanged += OnSchemeChanged;
    void OnDisable() => playerInput.onControlsChanged -= OnSchemeChanged;

    void OnSchemeChanged(PlayerInput pi)
    {
        promptImage.sprite = pi.currentControlScheme.Contains("Gamepad") ? padIcon : kbIcon;
    }
}

For Local Multiplayer

Use PlayerInputManager. Auto-Switch on individual PlayerInputs would steal devices from other players. PlayerInputManager handles join/leave with explicit device claims.

Verifying

Start with keyboard. Press a gamepad button. Player should swap; OnSchemeChanged fires; UI updates. Plug/unplug controllers; same behavior.

“Auto-Switch on. Subscribe to onControlsChanged. Multiplayer uses PlayerInputManager.”

Related Issues

For OnScreenStick not tracking, see OnScreenStick. For Steam Input action sets, see Steam Input.

Auto-Switch. Subscribe. Prompts update.