In what scenarios might unexpected behavior, such as missing session variables, occur when using sessions in PHP?

Unexpected behavior, such as missing session variables, might occur when using sessions in PHP due to issues with session initialization, expiration, or storage. To solve this problem, ensure that session_start() is called at the beginning of every script that needs to access session variables, set appropriate session configuration options, and handle potential errors gracefully. 

session_start();
// Check if session variable is set
if(isset($_SESSION['variable_name'])) {
    // Use the session variable
} else {
    // Handle the missing session variable
}

Keywords

session variables PHP unexpected behavior scenarios missing

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