Toggle.isOn= var calls StackOverflowException+ Logs

[SerializeField] private Toggle fullscreenToggle; //selected in inspector
private bool doShowFullscreen;
public void Start()
doShowFullscreen = (PlayerPrefs.GetInt(“doShowFullscreen”) == 0);

         fullscreenToggle.isOn = false; //ok
         fullscreenToggle.isOn = true; //ok
         fullscreenToggle.isOn = doShowFullscreen; //StackOverflowException


[MODES] Loading mode Default (0) for mode-current-id-Pirates: Mystery of Skeleton Island
Mono: successfully reloaded assembly

  • Completed reload, in 1.728 seconds
    Platform modules already initialized, skipping

what is the problem again? Plz give more detial