Troubleshooting

About 10 minutes, only if something failed.

Learning objectives

Match a symptom to one cause
Fix Active Input Handling, project-wide actions, and script setup without guessing

Work top to bottom. Change one thing, then retest in Play mode.

Quick checks

Symptom	First thing to verify
Nothing happens when you press keys	You are in Play mode and the Game view has focus
`InputAction` will not compile	`using UnityEngine.InputSystem;` is at the top of the script
`FindAction` returns null	Project-wide asset is assigned; the path is `"Player/Move"`
Cube sits still	`PlayerMover` is on `Player` and enabled; `moveSpeed` is not `0`
UI clicks do nothing	EventSystem uses Input System UI Input Module
`Input.GetAxis` / `Input.GetKey` errors	Active Input Handling is New; delete that legacy code

Editor did not restart after Active Input Handling

Edit > Project Settings > Player > Other Settings > Configuration > Active Input Handling only applies after an Editor restart.

Set it to Input System Package (New) again.
Close Project Settings.
If Unity did not prompt, close the Editor from File > Exit (or the window close button).
Reopen the project from Hub.
Recheck the dropdown.

You should see: Input System Package (New) is still selected after the restart.

`InputSystem.actions` is null, or FindAction returns null

InputSystem.actions is the project-wide Action Asset. If none is assigned, it is null. If the name is wrong, FindAction returns null and PlayerMover bails out in Update.

Open Edit > Project Settings > Input System Package.
If there is no asset, select Create and assign a default project-wide Action Asset.
In PlayerMover, use FindAction("Player/Move"), not "Move" and not "player/move".
Open the .inputactions asset and confirm the map is named Player and the action is named Move.

You should see: InputSystem.actions is assigned, and a temporary Debug.Log(moveAction) in Start is not null. Remove the log after it works.

Cube does not move

Run these in order:

Confirm you pressed Play. Edit mode will not run this movement.
Click the Game view so keyboard focus is not in the Scene view, Console, or a text field.
Select Player. Confirm Player Mover is present and enabled.
Confirm Move Speed is greater than 0.
Confirm you did not also leave a disabled script as the only component — the enabled one must be PlayerMover (page 05) or PlayerMoverEvents (page 06), not both enabled.
Search your scripts for Input.GetAxis or Input.GetKey. Delete those calls. They are the old Input Manager and fail when Active Input Handling is New.
Add this inside Update after ReadValue, play, and hold W:

Debug.Log(move);

(0.00, 0.00) while holding W means the action is not receiving keyboard input (wrong map, Game view unfocused, or backends not enabled).
(0.00, 1.00) means input works and the transform code is the problem (you are translating along the wrong axes, or the camera is looking so the motion is hard to see).

CS0246: InputAction could not be found

The compiler cannot see the Input System types.

Confirm the first two lines of the script are:

using UnityEngine;
using UnityEngine.InputSystem;

Confirm Window > Package Manager shows Input System installed.
Confirm Active Input Handling is Input System Package (New) or Both, then restart the Editor.
Wait for the script to recompile.

InputAction lives in UnityEngine.InputSystem, not in UnityEngine.

UI / EventSystem broken after switching

When Active Input Handling is New or Both, uGUI needs Input System UI Input Module. Standalone Input Module talks to the old Input Manager.

Select EventSystem in the Hierarchy (Unity creates it when you add a Canvas).
If the Inspector shows Standalone Input Module, remove it.
Add Component > Input System UI Input Module.
If Unity shows a button to replace the old module, use that button.

This starter does not need a Canvas. Only do this if UI clicks or Submit stopped working.

Both vs New, leftover Input Manager code

Active Input Handling	`Input.GetKey` / `Input.GetAxis`	Input System actions
Input Manager (Old)	Works	Does not
Input System Package (New)	Does not	Works
Both	Works	Works

This course is New. If a tutorial or autocomplete inserts Input.GetAxis("Horizontal"), do not keep it. Both exists so an old project can migrate one script at a time. It also lets students "fix" a broken script by turning the old API back on. Leave Both off unless your instructor says otherwise.

Defines you may see in code:

ENABLE_INPUT_SYSTEM when the new backends are on
ENABLE_LEGACY_INPUT_MANAGER when the old backends are on

Package missing after a Hub template without Keep Project Settings

If you created this project from a custom course template and Package Manager shows Input System but Active Input Handling is still Input Manager (Old), the template was saved with Keep Project Settings off.

That is an instructor fix. See Save as a course template. Until it is fixed:

Set Active Input Handling to Input System Package (New) yourself.
Restart the Editor.
Assign the project-wide Action Asset if it is missing.

Player Input events never fire

Behavior must be Invoke Unity Events.
Default Map must be Player.
The event function must be public void OnMove(InputAction.CallbackContext context) (or OnJump with the same signature).
The dropdown must show PlayerMoverEvents.OnMove, not a MonoBehaviour method with no arguments.
Disable PlayerMover so it is not competing, and do not read InputSystem.actions from the same object.

Jump logs three times if you skip if (context.performed).

Checkpoint

You can continue when:

Play mode moves the cube with WASD or arrows
The Console has no compile errors
Active Input Handling is Input System Package (New)