What are the common errors that can occur when trying to access objects from PHP sessions on another page?

Common errors that can occur when trying to access objects from PHP sessions on another page include not starting the session with `session_start()` on the page where you want to access the session data, and not serializing and unserializing objects properly before storing and retrieving them from the session. To solve this, make sure to start the session on each page where you want to access session data and properly serialize and unserialize objects before storing and retrieving them.

// Page where session data is stored
session_start();
$_SESSION['user'] = serialize($userObject);

// Page where session data is accessed
session_start();
$userObject = unserialize($_SESSION['user']);