INPUT.GETKEY / GETKEYDOWN NOT WORKING IN UNITY

Why Are Inputs Missed or Ignored?

There are three primary reasons why Input.GetKeyDown() fails to register in Unity:

• 1. Polling Input in FixedUpdate(): FixedUpdate() runs at a fixed 50Hz (every 20ms), while Update() runs with every rendered screen frame (e.g. 144Hz = 6.9ms). Input.GetKeyDown is only true for one single render frame. If you tap the key in a frame where FixedUpdate does not tick, the input is permanently lost!
• 2. UI Canvas Raycast Blocking: An invisible full-screen UI Image or panel has Raycast Target checked, intercepting mouse clicks or touch taps before they reach the game world.
• 3. Active Input System Mismatch: The project is configured for the New Input System Package while the script is using the legacy UnityEngine.Input API.

Step-by-Step Fix

1. Always Poll Inputs in Update():

   Read keydown flags inside Update(), store them in a boolean variable, and execute the physical force in FixedUpdate():

   Copy Code

   private bool jumpRequested;
   
   void Update()
   {
       // ✅ Never missed in Update!
       if (Input.GetButtonDown("Jump"))
       {
           jumpRequested = true;
       }
   }
   
   void FixedUpdate()
   {
       if (jumpRequested)
       {
           rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
           jumpRequested = false; // Reset
       }
   }

2. Disable Raycast Target on Non-Interactive UI:

   Select your UI Canvas backgrounds, health bars, and HUD overlays. In the Image and TextMeshProUGUI components, UNCHECK Raycast Target.

3. Check Active Input Handling Setting:

   Go to Project Settings > Player > Other Settings > Active Input Handling. If using legacy code alongside new controllers, select Both.

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