Session variable disappears after using the insert function

I have on my site where I display the username as a session variable in the header of the website. When I navigate between the pages, the session variable remains, but on one of my pages I am using a modal box with a form inside. When the user clicks on the submit button the insert function is saving the data to the database, but that username session variable disappears but the logout function is still visible on the website.

The weird thing is if I remove the insert function and then hit the submit button, of course the page doesn't do anything but refresh, but the session variable does not disappear. On another page where I have an update function, the session variable does not disappear.

Do you have any idea what this could be?

Make sure you have @session_start() before setting or referring to any session variables. Maybe it isn't started on that page?

Another issue could be in a .htaccess file if the page in question is in a different folder... different folders can be configured to have a different session through .htaccess.

It is started on that page because when you navigate to that page you see that username session variable. When I click on the link that opens the modal box and then hit the submit button, I set the success redirect to return to the same page and when the page comes back up then the username session variable is gone.

If you want to give me FTP access and steps to reproduce I can try debugging. The only thing I can think is that there wasn't a session_start() when the session variables were saved in the first place.

Let me ask this, when you use mysqli to make a connection to database it starts a session. would I need to add session start to every page including the ones that include the connection file?

Even though it starts the session, it will close it when it thinks it is done. You can access and view session variables after the session is closed, but you can't store or update them.

Whenever you are storing or updating a session variable you should add a line to make sure the session is started above it:
@session_start()

You should probably also close the session once you are done for efficiency particularly if you are using AJAX on your site:
session_commit();