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Resolved Object reference not set to instance of an object

Discussion in 'Scripting' started by jlorenzi, Jan 15, 2022.

  1. jlorenzi

    jlorenzi

    Joined:
    May 2, 2021
    Posts:
    201
    I'm making a way for the player to select different levels, so I made a function that updates the level selection UI to show the unplayed levels as locked, but it's giving me this error
    NullReferenceException Object reference not set to instance of an object

    Fix: I made a variable for the script that contains the function to update the level selection UI in a different script so I could call it whenever. The problem was that I forgot to assign the variable in the editor.
     
  2. Kurt-Dekker

    Kurt-Dekker

    Joined:
    Mar 16, 2013
    Posts:
    29,608
    As you already found out, the answer is always the same... ALWAYS. It is the single most common error ever.

    Don't waste your life spinning around and round on this error. Instead, learn how to fix it fast... it's EASY!!

    Some notes on how to fix a NullReferenceException error in Unity3D
    - also known as: Unassigned Reference Exception
    - also known as: Missing Reference Exception
    - also known as: Object reference not set to an instance of an object

    http://plbm.com/?p=221

    The basic steps outlined above are:
    - Identify what is null
    - Identify why it is null
    - Fix that.

    Expect to see this error a LOT. It's easily the most common thing to do when working. Learn how to fix it rapidly. It's easy. See the above link for more tips.

    You need to figure out HOW that variable is supposed to get its initial value. There are many ways in Unity. In order of likelihood, it might be ONE of the following:

    - drag it in using the inspector
    - code inside this script initializes it
    - some OTHER external code initializes it
    - ? something else?

    This is the kind of mindset and thinking process you need to bring to this problem:

    https://forum.unity.com/threads/why-do-my-music-ignore-the-sliders.993849/#post-6453695

    Step by step, break it down, find the problem.

    Here is a clean analogy of the actual underlying problem of a null reference exception:

    https://forum.unity.com/threads/nul...n-instance-of-an-object.1108865/#post-7137032

    Posting in the forum is not the right way to fix the error.
     
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