Sharing violation on path... Save Game Issue.

Hello, I am trying to make a save game system for my game but this error is making problems for it.

Here is the code: (SaveSystem.cs)

 using UnityEngine;
 using System.IO;
 using System.Runtime.Serialization.Formatters.Binary;
 
 public static class SaveSystem
 {
     public static void SaveProgress (StartGame level)
     {
         BinaryFormatter formatter = new BinaryFormatter();
 
         string path = Application.persistentDataPath + "/game.dat";
         FileStream stream = new FileStream(path, FileMode.OpenOrCreate);
 
         PlayerData data = new PlayerData(level);
 
         formatter.Serialize(stream, data);
         stream.Close();
     }
 
     public static PlayerData LoadProgress()
     {
         string path = Application.persistentDataPath + "/game.dat";
 
         if(File.Exists(path))
         {
             BinaryFormatter formatter = new BinaryFormatter();
             FileStream stream = new FileStream(path, FileMode.Open);
 
             PlayerData data = formatter.Deserialize(stream) as PlayerData;
             stream.Close();
 
             return data;
         }
         else
         {
             Debug.Log("Save file not found.");
             return null;
         }
     }
 }
 

PlayerData.cs

 using UnityEngine;
 
 [System.Serializable]
 public class PlayerData : MonoBehaviour
 {
     public int GameProgress;
 
     public PlayerData(StartGame level)
     {
         GameProgress = level.GameProgress;
     }
 }
 

And at last: (StartGame.cs)

 using UnityEngine;
 using UnityEngine.SceneManagement;
 using UnityEngine.UI;
 
 public class StartGame : MonoBehaviour
 {
     public int GameProgress = 0;
     public void StartGamePlay()
     {
             SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 4);
     }
 
     public void BackToMenu()
     {
         SceneManager.LoadScene(1);
     }
 
     public void LoadLevelScene()
     {
         SceneManager.LoadScene(2);
     }
 
     public void LoadOptionsScene()
     {
         SceneManager.LoadScene(3);
     }
 
     private void Update()
     {
         int CurrentLevel = SceneManager.GetActiveScene().buildIndex;
 
         if(CurrentLevel == 6)
         {
             GameProgress = 1;
             Debug.Log(GameProgress + "       " + CurrentLevel);
             SaveGameProgress();
         }
     }
 
 
     public void SaveGameProgress()
     {
         SaveSystem.SaveProgress(this);
     }
 
     public void LoadGameProgress()
     {
         PlayerData Data = SaveSystem.LoadProgress();
 
         GameProgress = Data.GameProgress;
     }
     public void ContinueGame()
     {
         LoadGameProgress();
         if(GameProgress == 1)
         {
             SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 5);
         }
         else if (GameProgress == 2)
         {
             SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 6);
         }
         else
         {
             Debug.Log("Game Progress is Null");
         }
     }
 }
 

The error I am getting when I am on scene 6 is "Sharing violation on path ..."Directory" ".