What are some common challenges faced when customizing forum scripts or CMS systems for specific functionalities in PHP?

One common challenge faced when customizing forum scripts or CMS systems for specific functionalities in PHP is ensuring compatibility with existing code and plugins. This can be particularly tricky when trying to integrate new features or modify existing ones without breaking the overall functionality of the system. It is important to thoroughly test any changes made to ensure they work as intended and do not introduce any bugs or conflicts.

// Example code snippet for adding a custom functionality to a forum script
// Ensure to check for existing functions or hooks that can be utilized to avoid conflicts

// Hook into the forum script to add a custom functionality
add_action('forum_custom_function', 'custom_forum_function');

function custom_forum_function() {
    // Custom functionality code here
}