How do I Remove null components ( i.e. "Missing(Mono Script)" ) via editor script?

Question

I have made a script somewhat similar to this one: http://answers.unity3d.com/questions/5020/searching-a-project-for-missing-mono-script

But rather than just finding the null entries, I simply want to sweep through and delete them all. By that I mean remove the null references from the GameObjects's list of Components.

The documentation for GameObject.AddComponent notes that there is no such thing as RemoveComponent, requiring you to call Object.Destroy() to remove that entry. This is impossible because there is no object to Destroy.

Creating a new GameObject and adding the components of the old one to it would invalidate any references to it.

Is there a way to do this without laboriously clicking through the UI?

NEW EDIT: (in light of comments below)

Are these references to some funny objects representing a missing script that the overloaded == operator is treating as equal to null? No, because calling DestroyImmediate() does nothing, and trying to actually de-reference the pointer causes a null reference exception. It must be that there are null pointer entries in the list, and the list is not modifiable by editor script.

Here is the demonstration code:

[MenuItem("Custom/Remove Missing Script Entries")]
public static void Do() {
    foreach (Transform t in Selection.transforms) {
        Debug.Log(t.GetComponents(typeof(Component)).Length);
        foreach (Component c in t.GetComponents(typeof(Component))) {
            if (c == null){
                Debug.Log("NULL");
                // throw caution to the wind and destroy anyway!!! AHAHHAHAHAH!!!
                GameObject.DestroyImmediate(c);
                // awwww nothing happened.  still there.
            }
            else
                Debug.Log(c.GetType());
        }
    }
}

Answer 1

They have added a fix for this in 2019.1

https://docs.unity3d.com/2019.1/Documentation/ScriptReference/GameObjectUtility.RemoveMonoBehavioursWithMissingScript.html

Edit: Code example

 [MenuItem("Auto/Remove Missing Scripts Recursively")]
 private static void FindAndRemoveMissingInSelected()
 {
     var deepSelection = EditorUtility.CollectDeepHierarchy(Selection.gameObjects);
     int compCount = 0;
     int goCount = 0;
     foreach (var o in deepSelection)
     {
         if (o is GameObject go)
         {
             int count = GameObjectUtility.GetMonoBehavioursWithMissingScriptCount(go);
             if (count > 0)
             {
                 // Edit: use undo record object, since undo destroy wont work with missing
                 Undo.RegisterCompleteObjectUndo(go, "Remove missing scripts");
                 GameObjectUtility.RemoveMonoBehavioursWithMissingScript(go);
                 compCount += count;
                 goCount++;
             }
         }
     }
     Debug.Log($"Found and removed {compCount} missing scripts from {goCount} GameObjects");
 }

Edit2: Sorry didn't see @AlanMattano posted this in a comment a while ago.

Edit3: For this to work on inactive Objects and prefabs, the code is a bit more complicated:

 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;
 using UnityEditor;
 public static class FindMissingScriptsRecursively
 {
     [MenuItem("Auto/Remove Missing Scripts Recursively Visit Prefabs")]
     private static void FindAndRemoveMissingInSelected()
     {
         // EditorUtility.CollectDeepHierarchy does not include inactive children
         var deeperSelection = Selection.gameObjects.SelectMany(go => go.GetComponentsInChildren<Transform>(true))
             .Select(t => t.gameObject);
         var prefabs = new HashSet<Object>();
         int compCount = 0;
         int goCount = 0;
         foreach (var go in deeperSelection)
         {
             int count = GameObjectUtility.GetMonoBehavioursWithMissingScriptCount(go);
             if (count > 0)
             {
                 if (PrefabUtility.IsPartOfAnyPrefab(go))
                 {
                     RecursivePrefabSource(go, prefabs, ref compCount, ref goCount);
                     count = GameObjectUtility.GetMonoBehavioursWithMissingScriptCount(go);
                     // if count == 0 the missing scripts has been removed from prefabs
                     if (count == 0)
                         continue;
                     // if not the missing scripts must be prefab overrides on this instance
                 }
 
                 Undo.RegisterCompleteObjectUndo(go, "Remove missing scripts");
                 GameObjectUtility.RemoveMonoBehavioursWithMissingScript(go);
                 compCount += count;
                 goCount++;
             }
         }
 
         Debug.Log($"Found and removed {compCount} missing scripts from {goCount} GameObjects");
     }
 
     // Prefabs can both be nested or variants, so best way to clean all is to go through them all
     // rather than jumping straight to the original prefab source.
     private static void RecursivePrefabSource(GameObject instance, HashSet<Object> prefabs, ref int compCount,
         ref int goCount)
     {
         var source = PrefabUtility.GetCorrespondingObjectFromSource(instance);
         // Only visit if source is valid, and hasn't been visited before
         if (source == null || !prefabs.Add(source))
             return;
 
         // go deep before removing, to differantiate local overrides from missing in source
         RecursivePrefabSource(source, prefabs, ref compCount, ref goCount);
 
         int count = GameObjectUtility.GetMonoBehavioursWithMissingScriptCount(source);
         if (count > 0)
         {
             Undo.RegisterCompleteObjectUndo(source, "Remove missing scripts");
             GameObjectUtility.RemoveMonoBehavioursWithMissingScript(source);
             compCount += count;
             goCount++;
         }
     }
 }

Answer 2

Answer by SunnySunshine · Jan 27, 2015 at 11:59 AM

By using this editor script, you can select all objects that are missing scripts, and then just delete them using the component menu.

Note that this will only work for missing scripts of the same type.

 [MenuItem("MyMenu/SelectMissing")]
 static void SelectMissing(MenuCommand command)
 {
     Transform[] ts = FindObjectsOfType<Transform>();

     List<GameObject> selection = new List<GameObject>();

     foreach(Transform t in ts)
     {
         Component[] cs = t.gameObject.GetComponents<Component>();

         foreach(Component c in cs)
         {
             if (c == null)
             {
                 selection.Add(t.gameObject);
             }
         }
     }

     Selection.objects = selection.ToArray();
 }

alt text

screen-shot-2015-01-27-at-125708-pm.png (24.5 kB)

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akasurreal · Aug 30, 2015 at 11:10 PM 2

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This works great, thanks.

Kjurek · Oct 13, 2017 at 12:13 PM 0

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Just perfect. Thx!

Answer 3

Answer by beck · Dec 27, 2014 at 08:14 AM

Ran into this myself and ended up with a working solution. Only works in the editor of course.

 [MenuItem("Edit/Cleanup Missing Scripts")]
 static void CleanupMissingScripts ()
 {
     for(int i = 0; i < Selection.gameObjects.Length; i++)
     {
         var gameObject = Selection.gameObjects[i];
         
         // We must use the GetComponents array to actually detect missing components
         var components = gameObject.GetComponents<Component>();
         
         // Create a serialized object so that we can edit the component list
         var serializedObject = new SerializedObject(gameObject);
         // Find the component list property
         var prop = serializedObject.FindProperty("m_Component");
         
         // Track how many components we've removed
         int r = 0;
         
         // Iterate over all components
         for(int j = 0; j < components.Length; j++)
         {
             // Check if the ref is null
             if(components[j] == null)
             {
                 // If so, remove from the serialized component array
                 prop.DeleteArrayElementAtIndex(j-r);
                 // Increment removed count
                 r++;
             }
         }
         
         // Apply our changes to the game object
         serializedObject.ApplyModifiedProperties();
     }
 }

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beck · Dec 27, 2014 at 08:22 AM 0

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Just want to note that I found out that the components reappear after reloading assemblies. However, if you perform this function, save the scene, and then change scenes, the fix sticks. It's hacky, but it works for me. Would love to see a more stable solution if someone finds one.

xiaomu beck · Oct 23, 2015 at 09:46 AM 0

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I get the same trouble, Did you find a solution ?

meat5000 ♦ xiaomu · Oct 23, 2015 at 10:09 AM 0

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If you are trouble removing a "$$anonymous$$issing Script" Component, simply drop a script into it, then remove it, in Editor.

Save.

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IgorAherne beck · Sep 16, 2017 at 12:15 PM 0

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will this fix the issue at the end of the function?

 UnityEditor.Scene$$anonymous$$anagement.EditorScene$$anonymous$$anager.$$anonymous$$arkSceneDirty(gameObject.scene);

Gerold_Meisinger · Mar 03, 2016 at 07:44 AM 0

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Thanks for the solution! Btw: If you iterate the array in reverse you can omit keeping track of deleted elements. I also marked the GameObjects dirty. Works for me in U 5.1.4 but Unity crashes with a memory alloc error on changing scene afterwards. It still works though!

zero_null Gerold_Meisinger · May 31, 2016 at 01:27 PM 0

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Hey Hi @Gerold_meisinger

Can you tell me how you set GameObjects dirty ? Please

IgorAherne zero_null · Sep 17, 2017 at 02:51 AM 0

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 UnityEditor.EditorUtility.SetDirty(myGameObject);

you can also wrap it in preprocessor like this

 #if UNITY_EDITOR
 UnityEditor.EditorUtility.SetDirty(myGameObject);
 #endif

this will exclude this portion of code when the game is built, as if it never existed; Useful when you need to include "UnityEditor" functionality right into a $$anonymous$$onobehavior

NeatWolf · Jul 29, 2018 at 01:04 PM 0

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Thanks, in Unity 2018.2.1f1 I found myself with ALL gameobjects and prefabs in the project with an invisible script missing.

That meant that I had a "You are trying to replace or create a prefab from the instance 'Arch_Door_04_Preset' that references a missing script. This is not allowed. Please change the script or remove it from the game object. UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) " every time I tried to apply changes from an instance to a Prefab.

Now I should only adapt your script to work on the whole Scene and Project Hierarchy and I should be able to save the project, which got corrupted in some way, and I didn't even noticed when!

AlanMattano · Jan 30, 2019 at 12:40 AM 1

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In the new Unity2019.1 API notes I read:

Editor: Added GameObjectUtility.Get$$anonymous$$onoBehavioursWith$$anonymous$$issingScriptCount and GameObjectUtility.Remove$$anonymous$$onoBehavioursWith$$anonymous$$issingScript to be able to remove $$anonymous$$onoBehaviours with a missing script from a game object.

VildNinja AlanMattano · Mar 25, 2019 at 10:13 AM 0

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Sorry didn't see you posted this before now. I've added a code example of this below.

Answer 4

Answer by jonas-echterhoff · Jun 28, 2010 at 08:50 AM

I believe there is currently no easy solution to do this in scripting. The internal implementation when you pick "Remove Component" from the popup menu is in C++, where all MonoBehaviour components are just belonging to a MonoBehaviour class. Once these are passed to C#, they get the class types of their scripts, or, if the script is empty, then null, which cannot be used to destroy the object.

You might be able to get a pointer reference to the actual MonoBehaviour component which you could call delete on, by iterating through all the GameObjects properties using the SerializedObject class, but that probably takes same time to get to work, if it is possible at all.

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Bunny83 · May 12, 2012 at 03:20 PM 0

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Just want to add that i've just tried to get a usable reference to the $$anonymous$$onoBehaviour, but it seems there's really no way. I used the SerializedObject class to get all component references, but even there it's just null.

I've digged quite deep into the editor and realized that the default inspector also uses a serialized object to display the GUI. The editor creates a SerializedObject from a reference, but this reference seems to get passed from the native code side. $$anonymous$$aybe it's possible to "hack" into the private members of the editor that displays the $$anonymous$$onoBehaviour with reflection, but beside that it's not a good idea to use relfection that way, it won't help much since the information what $$anonymous$$onoScript was used by this Behaviour is gone.

Answer 5

Answer by DannyLZS · Jun 19, 2017 at 06:57 PM

Wrote a solution

https://pastebin.com/DLuE2Ze9

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TooManySugar · Aug 20, 2018 at 11:30 AM 0

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THAN$$anonymous$$ YOU!!! THIS WOR$$anonymous$$S PERFECTLY, this should be the accepted answer

TheGameLearner TooManySugar · Nov 04, 2019 at 07:34 AM 0

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Running into the following after using this:

 Transform has 'ReflectionProbeAnchor$$anonymous$$anager::kChangeSystem' change interests present when destroying the hierarchy. Interests must be deregistered in Deactivate.
 UnityEditor.EditorApplication:Internal_CallGlobalEventHandler()

Can you tell me what can I do to avoid it?

How do I Remove null components ( i.e. "Missing(Mono Script)" ) via editor script?

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