GameObject is already being activated or desactivated

When I jump into the moving platform they show my this error.

 void OnCollisionEnter2D(Collision2D other)
     {
         if (other.transform.tag == "MovingPlatform")
         {
             transform.parent = other.transform;
         }
     }
 
     void OnCollisionExit2D(Collision2D other)
     {
         if (other.transform.tag == "MovingPlatform")
         {
             transform.parent = null;
         }
     }

The error is this line of code:

 transform.parent = null;