Instantiating UI Prefab - Error: Setting parent of a transform which resides in a prefab is disabled. What's wrong with my code?

Is the object put in the inspector for the variable "canvas" a prefab ?

@$$anonymous$$iraSensei - Yes, the canvas object set in the inspector is a prefab.

For what it's worth, the canvas itself was not modified in any way from its default, except that I added three UI prefab children to it (but not the BossHealth prefab, as I want that to be instantiated from a script).

So you have your answer :)

your script tries to put canvas as the parent of your current game object, but it is a prefab, and this is not allowed. It has to be a game object already existing in your scene (maybe an instantiation of your prefab canvas).

@$$anonymous$$iraSensei is right, no harm in using a prefab but you'd have to instantiate the prefab canvas and give that instance a unique name so you can use GameObject.Find to search for the instantiated canvas once it exists.

Or, as a canvas takes little resources on its own, just leave the canvas in the scene so you can still use your public statement.

You are not forced to find it after you create it :

 void Start () {
     GameObject canvasGO = (GameObject) Instantiate(canvas, transform.position, transform.rotation);
 
     transform.SetParent (canvasGO, false);
     ...
 }

Do you realize if you use

  Instantiate (bossHealthUI);

you have no way to reference this GameObject?

One of these might make your script work:

  this = Instantiate (bossHealthUI);
  transform = Instantiate (bossHealthUI);
  gameObject = Instantiate (bossHealthUI); //LOWERCASE G IS I$$anonymous$$PROTANT

True @$$anonymous$$iraSensei but @reinfeldx should really consider changing the way they're instantiating the canvas. At the moment we have the bosshealth prefab trying to set it's parent prefab which is O$$anonymous$$ if that's a known instantiated object or one that's just in the scene and not a prefab.

But to instantiate a panel/slider well any UI element and then instantiate the parent canvas within a script attached to that UI element, well I'm not saying it won't work but what happens if there's another element on that canvas that does the same, you could end up with canvases all over the place.

Or even why not put the bosshealth as part of the canvas that's instantiated so all done in one call.

Not trying to dictate how people build their game, just seems madness to me unless there's a specific reason for it.

Edit 2: I've got it working, but I still don't understand the behavior in the beginning of this comment.

I'm understanding now that I can't use a prefab to set the public "canvas" variable in the BossHealth script. However, I have an instance of the canvas already in the scene and I am unable to drop it into the Inspector.

The canvas will be in the scene from the start, so I have no problem trying to reference this instance ins$$anonymous$$d of the prefab. I'm just not sure why I can't set it in the Inspector. Edit 1: $$anonymous$$aybe I should note that I am trying to edit the BossHealth prefab directly in the prefab folder.

At this point I've also tried changing my declaration for canvas to a GameObject ins$$anonymous$$d of a Transform, like so:

     public GameObject canvas;
 
     void Start () {
         transform.SetParent (canvas.transform, false);

So now the Inspector is asking for a GameObject ins$$anonymous$$d of a Transform, but I am still unable to drag the canvas into it.

To answer @$$anonymous$$mmpies's question about why I'm not including BossHealth in the canvas that's instantiated - it's because I would like to only show BossHealth when the Boss is in the scene. The rest of the canvas includes UI elements that should be shown constantly, like Score and Lives.

Edit 2: The following approach worked for me. Setting it via code ins$$anonymous$$d of setting it in the Inspector after tagging the canvas.

     private GameObject canvas;
 
     void Start () {
         canvas = GameObject.FindGameObjectWithTag ("Canvas");
         transform.SetParent (canvas.transform, false);

I'd still like to know why the Inspector approach wasn't working.

So declare canvas as a game object in your script :)

 public GameObject canvas;

@$$anonymous$$iraSensei - Thanks, but I tried that. See 2/3 of the way down in my previous comment.

Oh, didn't see that, sorry.

There is no reason it should not work :(