What are common issues with form data submission in PHP?

Common issues with form data submission in PHP include not properly sanitizing user input, not validating input data, and not handling form submission errors effectively. To solve these issues, always sanitize user input to prevent SQL injection and other security vulnerabilities, validate input data to ensure it meets the expected format and requirements, and handle form submission errors by displaying helpful error messages to the user.

// Sanitize user input using htmlspecialchars to prevent XSS attacks
$name = htmlspecialchars($_POST['name']);
$email = htmlspecialchars($_POST['email']);

// Validate input data
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // Handle invalid email format error
    echo "Invalid email format.";
}

// Handle form submission errors
if (/* condition for form submission error */) {
    // Display error message to the user
    echo "An error occurred while submitting the form.";
}