What are common issues when users cannot log in to a PHP website?

Common issues when users cannot log in to a PHP website include incorrect username or password, session expiration, or database connection errors. To solve these issues, ensure that the user is entering the correct login credentials, check if the session is still valid, and verify that the database connection is working properly. 

// Check if the username and password are correct
if ($entered_username === $correct_username && $entered_password === $correct_password) {
    // Log the user in
} else {
    echo "Incorrect username or password";
}

// Check if the session is still valid
session_start();
if (isset($_SESSION['user_id'])) {
    // User is already logged in
} else {
    echo "Session expired, please log in again";
}

// Check if the database connection is working
$connection = mysqli_connect($host, $username, $password, $database);
if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
}

Keywords

authentication session management password hashing error handling SQL injection

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