How to serialize and save a GameObject in Unity
<p>I have a game where the player picks up a weapon and it is then placed as the GameObject variable to my player called "MainHandWeapon" and I am trying to save that weapon through scene changes so I am trying to save it.  How I handle this is as follows :</p>

<pre><code>public class Player_Manager : Character, Can_Take_Damage {

    // The weapon the player has.
    public GameObject MainHandWeapon;

    public void Save()
    {
        // Create the Binary Formatter.
        BinaryFormatter bf = new BinaryFormatter();
        // Stream the file with a File Stream. (Note that File.Create() 'Creates' or 'Overwrites' a file.)
        FileStream file = File.Create(Application.persistentDataPath + "/PlayerData.dat");
        // Create a new Player_Data.
        Player_Data data = new Player_Data ();
        // Save the data.
        data.weapon = MainHandWeapon;
        data.baseDamage = BaseDamage;
        data.baseHealth = BaseHealth;
        data.currentHealth = CurrentHealth;
        data.baseMana = BaseMana;
        data.currentMana = CurrentMana;
        data.baseMoveSpeed = BaseMoveSpeed;
        // Serialize the file so the contents cannot be manipulated.
        bf.Serialize(file, data);
        // Close the file to prevent any corruptions
        file.Close();
    }
}

[Serializable]
class Player_Data
{
    [SerializeField]
    private GameObject _weapon;
    public GameObject weapon{
        get { return _weapon; }
        set { _weapon = value; }
    }

    public float baseDamage;
    public float baseHealth;
    public float currentHealth;
    public float baseMana;
    public float currentMana;
    public float baseMoveSpeed;
}
</code></pre>

<p>But I keep getting this error from having this setup :</p>

<pre><code>SerializationException: Type UnityEngine.GameObject is not marked as Serializable.
</code></pre>

<p>What exactly am I doing wrong?</p>