What are the common reasons for session cookies expiring in PHP applications?

Session cookies in PHP applications commonly expire due to the default session cookie lifetime being set too short or the session.gc_maxlifetime configuration being too low. To solve this issue, you can adjust the session.cookie_lifetime or session.gc_maxlifetime values in your PHP configuration to a longer duration.

// Set session cookie lifetime to 1 hour
ini_set('session.cookie_lifetime', 3600);

// Set session garbage collection lifetime to 1 hour
ini_set('session.gc_maxlifetime', 3600);