nullreferenceexception: serializedobject of serializedproperty has been disposed

HaC 2025

3 min read 01-10-2024

nullreferenceexception: serializedobject of serializedproperty has been disposed

In the world of game development using Unity, encountering errors can often be an overwhelming experience, especially when they relate to serialization and object references. One such common error is NullReferenceException: SerializedObject of SerializedProperty has been disposed. In this article, we will delve into this specific error, analyze its potential causes, and provide practical solutions to mitigate it.

What Does This Error Mean?

The NullReferenceException generally occurs in Unity when you try to access a property or a method on an object that is set to null. In the context of SerializedObject and SerializedProperty, this error indicates that a reference to a serialized object has been disposed of or no longer exists, but there is still an attempt to access its properties.

Key Terms:

SerializedObject: A class in Unity that wraps a serialized object, allowing you to manipulate its serialized fields in the Editor.
SerializedProperty: Represents a single property (field) of a serialized object.

Example Situation

Imagine you are developing a game where you are customizing properties of a ScriptableObject in Unity. You might create a custom editor script to modify these properties through the Unity Inspector. If the SerializedObject you are trying to work with has been disposed—perhaps because the object was destroyed or the scene was unloaded—then accessing its SerializedProperty will throw the NullReferenceException.

Common Causes

Object Disposal: If the underlying object of the SerializedObject has been disposed (deleted), any attempt to access its properties will throw this error.
Editor Update Issues: Sometimes, if an editor script does not properly handle the changes in serialized objects (like creating or destroying objects), it can lead to discrepancies.
Improperly Managing Serialized Objects: Not properly updating the SerializedObject after changes can also lead to stale references.

Example Code

Here’s a snippet of a custom editor script that could lead to this error:

using UnityEditor;
using UnityEngine;

[CustomEditor(typeof(MyScriptableObject))]
public class MyScriptableObjectEditor : Editor
{
    SerializedObject serializedObject;
    SerializedProperty myProperty;

    void OnEnable()
    {
        serializedObject = new SerializedObject(target);
        myProperty = serializedObject.FindProperty("myField");
    }

    public override void OnInspectorGUI()
    {
        serializedObject.Update();
        EditorGUILayout.PropertyField(myProperty);
        serializedObject.ApplyModifiedProperties();
    }
}

In this script, if the MyScriptableObject gets disposed or destroyed before OnInspectorGUI() is called, accessing myProperty can cause the NullReferenceException.

Solutions

1. Checking for Null

Before accessing serialized properties, always check if the serialized object is null or disposed.

if (serializedObject != null)
{
    serializedObject.Update();
    EditorGUILayout.PropertyField(myProperty);
}

2. Reinitialize the Serialized Object

If your script can be interrupted or the object can be destroyed at runtime, consider reinitializing the SerializedObject on-demand within the OnInspectorGUI() method.

public override void OnInspectorGUI()
{
    if (serializedObject == null)
    {
        serializedObject = new SerializedObject(target);
        myProperty = serializedObject.FindProperty("myField");
    }

    serializedObject.Update();
    EditorGUILayout.PropertyField(myProperty);
    serializedObject.ApplyModifiedProperties();
}

3. Utilize Unity Events

Implementing event listeners (like OnDestroy) to handle when objects are disposed can help in managing serialized objects better.

private void OnDestroy()
{
    serializedObject.Dispose();
}

Additional Best Practices

Documentation and Comments: Always document your code. Comment on the critical sections of the code that manage serialized objects, making it easier to understand their lifecycle.
Test for Edge Cases: Always test your editor scripts under different scenarios—what happens when objects are deleted or scenes are unloaded.
Editor Profiling: Utilize Unity’s profiling tools to ensure that serialized properties are being managed efficiently.

Conclusion

The NullReferenceException: SerializedObject of SerializedProperty has been disposed error is common in Unity but can be effectively managed with the right practices. By implementing null checks, reinitializing serialized objects, and handling Unity events properly, developers can prevent this error from disrupting their workflow. Remember, understanding the underlying mechanics of serialization in Unity is key to creating robust editor extensions and scripts.