Question Null Reference Exception ERROR: How to Pick up and Drop Objects/Items! (Unity Tutorial)

Hello forums community I am doing the How to Pick up and Drop Objects/Items! (First and Third Person, Unity Tutorial) on YouTube and will try to add my own twist to it after. I can pick up the item but not drop it with the same key. (I am open to using another key in the end if all else fails) But I keep getting this error:

NullReferenceException: Object reference not set to an instance of an object
PlayerPickUpDrop.Update () (at Assets/Scripts/PlayerPickUpDrop.cs:26)

These are the two main scripts:


using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ObjectGrabbable : MonoBehaviour {
private Rigidbody objectRigidbody;
private Transform objectGrabPointTransform;
private void Awake() {
objectRigidbody = GetComponent<Rigidbody>();
}
public void Grab(Transform objectGrabPointTransform) {
this.objectGrabPointTransform = objectGrabPointTransform;
objectRigidbody.useGravity = false;
}
public void Drop() {
this.objectGrabPointTransform = null;
objectRigidbody.useGravity = true;
}
private void FixedUpdate() {
if (objectGrabPointTransform != null) {
//lerpSPeed sets a target on how it smoothly follows and interpolate the movements.
float lerpSpeed = 10f;
Vector3 newPosition = Vector3.Lerp(transform.position, objectGrabPointTransform.position, Time.deltaTime * lerpSpeed);
objectRigidbody.MovePosition(objectGrabPointTransform.position);
}
}
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlayerPickUpDrop : MonoBehaviour {
[SerializeField] private Transform playerCameraTransform;
[SerializeField] private Transform objectGrabPointTransform;
[SerializeField] private LayerMask pickUpLayerMask;
private ObjectGrabbable objectGrabbable;

private void Update() {
if (Input.GetKeyDown(KeyCode.E)) {
if (objectGrabbable == null) {
//not carrying an object, try to grab
float pickUpDistance = 2f;
if (Physics.Raycast(playerCameraTransform.position, playerCameraTransform.forward, out RaycastHit raycastHit, pickUpDistance, pickUpLayerMask)) Debug.Log(raycastHit, transform);
if (raycastHit.transform.TryGetComponent(out objectGrabbable)) {
objectGrabbable.Grab(objectGrabPointTransform);
}
}
} else {
// Currently carrying something, drop
objectGrabbable.Drop();
objectGrabbable = null;
//get a conosole readout if the object is hit with the ray
Debug.Log("No game object called objectGrabble found");
}
}
}

I'd greatly appreciate any solution for this.

 

Kurt is obviously not up at this time of day, so I'll jump in:
How to fix a NullReferenceException error - Unity Forum
Everything you need is in there and it is worth learning.
Please use CodeTags as well.

 

This.

You did post the error including the line number, which is great. But as is, we have to count to find the line in question. Doing so, line 26 in the given code snipplet would be the Debug.Log() statement, which makes no sense. Always use code tags, post the full error including the line number, and make sure the line number matches between the code snipplet, your code, and the error message.

Other than that, Kurts writedown will help you through null reference exceptions. Very common, always the same approach. If you still have troubles feel free to ask, after adding code tags

 

This is a wonderful idea, but make sure you complete Step #2 below FIRST... or you will be wasting your time.

Tutorials and example code are great, but keep this in mind to maximize your success and minimize your frustration:

How to do tutorials properly, two (2) simple steps to success:

Step 1. Follow the tutorial and do every single step of the tutorial 100% precisely the way it is shown. Even the slightest deviation (even a single character!) generally ends in disaster. That's how software engineering works. Every step must be taken, every single letter must be spelled, capitalized, punctuated and spaced (or not spaced) properly, literally NOTHING can be omitted or skipped.

Fortunately this is the easiest part to get right: Be a robot. Don't make any mistakes.
BE PERFECT IN EVERYTHING YOU DO HERE!!

If you get any errors, learn how to read the error code and fix your error. Google is your friend here. Do NOT continue until you fix your error. Your error will probably be somewhere near the parenthesis numbers (line and character position) in the file. It is almost CERTAINLY your typo causing the error, so look again and fix it.

Step 2. Go back and work through every part of the tutorial again, and this time explain it to your doggie. See how I am doing that in my avatar picture? If you have no dog, explain it to your house plant. If you are unable to explain any part of it, STOP. DO NOT PROCEED. Now go learn how that part works. Read the documentation on the functions involved. Go back to the tutorial and try to figure out WHY they did that. This is the part that takes a LOT of time when you are new. It might take days or weeks to work through a single 5-minute tutorial. Stick with it. You will learn.

Step 2 is the part everybody seems to miss. Without Step 2 you are simply a code-typing monkey and outside of the specific tutorial you did, you will be completely lost. If you want to learn, you MUST do Step 2.

Of course, all this presupposes no errors in the tutorial. For certain tutorial makers (like Unity, Brackeys, Imphenzia, Sebastian Lague) this is usually the case. For some other less-well-known content creators, this is less true. Read the comments on the video: did anyone have issues like you did? If there's an error, you will NEVER be the first guy to find it.

Beyond that, Step 3, 4, 5 and 6 become easy because you already understand!

Finally, when you have errors, don't post here... just go fix your errors! Here's how:



Remember: NOBODY here memorizes error codes. That's not a thing. The error code is absolutely the least useful part of the error. It serves no purpose at all. Forget the error code. Put it out of your mind.

The complete error message contains everything you need to know to fix the error yourself.

The important parts of the error message are:

- the description of the error itself (google this; you are NEVER the first one!)
- the file it occurred in (critical!)
- the line number and character position (the two numbers in parentheses)
- also possibly useful is the stack trace (all the lines of text in the lower console window)

Always start with the FIRST error in the console window, as sometimes that error causes or compounds some or all of the subsequent errors. Often the error will be immediately prior to the indicated line, so make sure to check there as well.

Look in the documentation. Every API you attempt to use is probably documented somewhere. Are you using it correctly? Are you spelling it correctly?

All of that information is in the actual error message and you must pay attention to it. Learn how to identify it instantly so you don't have to stop your progress and fiddle around with the forum.




As for the nullref itself, the answer is always the same... ALWAYS!

How to fix a NullReferenceException error

https://forum.unity.com/threads/how-to-fix-a-nullreferenceexception-error.1230297/

Three steps to success:
- Identify what is null <-- any other action taken before this step is WASTED TIME
- Identify why it is null
- Fix that