What best practices should be followed when handling form data in PHP to avoid errors like the one described in the thread?

The issue described in the thread is likely caused by not properly sanitizing and validating form data in PHP, which can lead to vulnerabilities like SQL injection or cross-site scripting. To avoid such errors, it is important to always sanitize and validate user input before processing it. This can be done by using functions like htmlspecialchars() to prevent XSS attacks and prepared statements to prevent SQL injection.

// Example of sanitizing and validating form data in PHP

// Assuming form data is submitted via POST method
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = htmlspecialchars($_POST["name"]);
    $email = filter_var($_POST["email"], FILTER_VALIDATE_EMAIL);
    
    // Validate email format
    if ($email === false) {
        // Handle invalid email format error
    }

    // Process the sanitized and validated data
    // e.g. insert into database using prepared statements
}