Question The type or namespace name 'MultiAimConstraint' could not be found

I am struggling to find out why this code throws this error:

The type or namespace name 'MultiAimConstraint' could not be found

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEditor.Animations.Rigging;
5.  
6. public class HeadLook : MonoBehaviour
7. {
8.  
9.     private MultiAimConstraint mac;
10.     void Start()
11.     {
12.         mac = GetComponent<MultiAimConstraint>();
13.     }
14.  
15.     // Update is called once per frame
16.     void Update()
17.     {
18.        
19.         float inputVertical = Input.GetAxis("Vertical");
20.         mac.weight = inputVertical;
21.     }
22. }
23.  

It's not complete code so ignore what it is trying to do. Just can't get rid of the error.
Yes I have added Animation Rigging in the package manager.

Thanks

 

same here =(

 

its crazy that this was working minutes ago... suddendly it stopped working.

PS.: UnityEditor.Animations.Rigging must be UnityEngine.Animations.Rigging