Sir any best guide how to solves this? session always destroy

[01-Sep-2020 10:11:40 Europe/Paris] PHP Warning: session_start(): Failed to decode session object. Session has been destroyed in D:\Data\session.php on line 13
[01-Sep-2020 10:11:40 Europe/Paris] PHP Notice: Undefined index: id in D:\Data\navigator_f.php on line 215
[01-Sep-2020 10:11:40 Europe/Paris] PHP Notice: Undefined index: position in D:\Data\navigator_f.php on line 233

i already search about it in stack overflow… but it doesnt solve the problem. in just a few seconds or minutes. it destroys again… :,(
just f*** ** my whole program…