导航到新页面后，PHP会话消失

Im having an issue with sessions for the past 2 months and before was working. In all the pages the session is started with:

      session_start();

Every interaction i will use in the page it work. For example change the website language from english to portuguese. After i navigate to another page the session is empty is not keep the session alive. This was working for the past 2 years. I already ask the server owner and there wasnt any update in the server.

Thanks.