ArgumentException: Cannot deserialize JSON to new instances of type

Im getting the error on my settings manager script.

SettingManager Script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using System.IO;
 
 public class SettingManager : MonoBehaviour {
 
     public Dropdown Vsync;
     public Dropdown resolutionDropdown;
     public Toggle windowToggle;
     public Dropdown AAdropdown;
     public Dropdown qualitySettings;
 
 
     public Resolution[] resolutions;
     public GameSettings gameSettings;
     
 
     /// <summary>
     /// Options 
     /// </summary>
     void OnEnable()
     {
 
         gameSettings = GetComponent<GameSettings>();
 
         windowToggle.onValueChanged.AddListener(delegate { OnFullscreenToggle(); });
         resolutionDropdown.onValueChanged.AddListener(delegate { OnResolutionChange(); });
         qualitySettings.onValueChanged.AddListener(delegate { OnTextureQualityChange(); });
         AAdropdown.onValueChanged.AddListener(delegate { OnAntiAliasingChange(); });
         Vsync.onValueChanged.AddListener(delegate { OnvSyncChange(); });
 
 
         resolutions = Screen.resolutions;
 
         foreach(Resolution resolution in resolutions)
         {
             resolutionDropdown.options.Add(new Dropdown.OptionData(resolution.ToString()));
         }
         if (File.Exists(Application.persistentDataPath + "/gamesettings.json") == true)
         {
             LoadSettings();
         }
     }
     public void OnFullscreenToggle()
     {
 
         gameSettings.fullscreen = Screen.fullScreen = windowToggle.isOn;
     }
 
     public void OnResolutionChange()
     {
         Screen.SetResolution(resolutions[resolutionDropdown.value].width, resolutions[resolutionDropdown.value].height, Screen.fullScreen);
         gameSettings.resolutionIndex = resolutionDropdown.value;
     }
 
     public void OnTextureQualityChange()
     {
         QualitySettings.masterTextureLimit = gameSettings.textureQuality = qualitySettings.value;
     }
 
     public void OnAntiAliasingChange()
     {
         QualitySettings.antiAliasing = (int)Mathf.Pow(2, AAdropdown.value);
         gameSettings.antialiasing = AAdropdown.value;
     }
 
     public void OnvSyncChange()
     {
         QualitySettings.vSyncCount = gameSettings.vSync = Vsync.value;
     }
 
 
 
 
     public void SaveSettings()
     {
         string jsonData = JsonUtility.ToJson(gameSettings, true);
         File.WriteAllText(Application.persistentDataPath + "/gamesettings.json", jsonData);
     }
 
     public void LoadSettings()
     {
         File.ReadAllText(Application.persistentDataPath + "/gamesettings.json");
         gameSettings = JsonUtility.FromJson<GameSettings>(File.ReadAllText(Application.persistentDataPath + "/gamesettings.json"));
 
        AAdropdown.value = gameSettings.resolutionIndex;
         Vsync.value = gameSettings.vSync;
        qualitySettings.value = gameSettings.textureQuality;
         resolutionDropdown.value = gameSettings.resolutionIndex;
          windowToggle.isOn = gameSettings.fullscreen;
 
         resolutionDropdown.RefreshShownValue();
 
     }
     // Use this for initialization
     void Start () {
        
     }
     
     // Update is called once per frame
     void Update () {
         
     }
 }

GameManager Script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GameSettings : MonoBehaviour {
 
 
     public bool fullscreen;
     public int textureQuality;
     public int antialiasing;
     public int vSync;
     public int resolutionIndex;
     
 
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         
     }
 
 }