I am facing a frustrating issue where my session variables are completely lost after I use header("Location: dashboard.php"). I call session_start() at the very top of my script, and the data saves correctly on the initial page, but once the redirect happens, the $_SESSION array comes up empty on the target page. Is this a permissions issue with the session.save_path, or am I missing a specific configuration in php.ini related to cookie domains and cross-site redirects?
3 answers
The most common reason for losing session data during a redirect is that PHP hasn't finished writing the session data to the disk or database before the script terminates and the browser moves to the next URL. When you call header("Location: ..."), the script often continues to execute in the background unless you explicitly stop it. To fix this, you should always call session_write_close(); immediately before your exit; or die(); statement after the header call. This forces PHP to save the session data and close the file lock, ensuring the next page can read the updated information. Also, verify that your session.cookie_path is set correctly; if it's too restrictive, the browser won't send the session cookie back to the new URL.
I've tried adding exit; after my redirects, but I’m still losing the session occasionally. If my site is switching between http:// and https:// during the redirect process, could the session.cookie_secure flag be causing the browser to drop the session cookie because it thinks the connection is no longer safe?
Sometimes the issue is simply whitespace. If you have even a single space or a Byte Order Mark (BOM) before your <?php tag, the headers are sent early, and session_start() will fail to send the session cookie.
I agree with Susan. I spent hours debugging a similar session issue only to find out there was a newline character at the end of an included config file. Using output buffering with ob_start() at the very beginning of your application can often prevent these "headers already sent" errors from breaking your sessions.
Matthew, you hit the nail on the head. If session.cookie_secure is enabled and you redirect to an HTTP page, the browser will refuse to send the cookie. Similarly, check your session.cookie_samesite settings. If it's set to 'Strict', and your redirect is coming from an external source or a different sub-domain, the browser might block the cookie. Ensure your protocol is consistent (always HTTPS) and that your domain configuration in the session settings matches your actual site URL perfectly.