WordPress Hook & Filter Deprecation: How to Safely Replace Hooks and Notify Developers

Sabuj Kundu 10th Nov 2025

When developing WordPress plugins or themes, there may come a time when you need to deprecate an existing action or filter hook. Deprecation allows you to maintain backward compatibility while informing developers that they should switch to a newer, modern hook. WordPress provides built-in functions for this purpose: do_action_deprecated() for actions and apply_filters_deprecated() for filters.

Why Deprecate Hooks?

• Maintain backward compatibility with older plugins and themes.
• Give developers clear guidance about which hooks to use instead.
• Keep your codebase clean and modern without breaking existing functionality.

Deprecating an Action Hook

Suppose you have an action hook show_cbxbookmark_btn that you want to deprecate in favor of cbxbookmark_button_show. Here’s the correct approach:

do_action_deprecated(
    'show_cbxbookmark_btn',      // Old hook name
    array( $post_id, $user_id ), // Arguments passed to the hook
    '3.2.0',                     // Version where it was deprecated
    'cbxbookmark_button_show',   // New hook name (optional)
    'The hook show_cbxbookmark_btn is deprecated. Use cbxbookmark_button_show instead.'
);

do_action( 'cbxbookmark_button_show', $post_id, $user_id );

This ensures that:

• The old hook still fires, maintaining backward compatibility.
• Developers see a deprecation notice in debug mode.
• New code can immediately use the modern hook.

Deprecating a Filter Hook

Filters are very similar. Suppose you want to deprecate cbxwpbookmarks_mybookmark_page_url in favor of cbxbookmark_mybookmark_page_url:

// Deprecated filter
$value = apply_filters_deprecated(
    'cbxwpbookmarks_mybookmark_page_url',
    array( esc_url( $my_bookmark_page_url ) ),
    '3.2.0',
    'cbxbookmark_mybookmark_page_url',
    'The filter cbxwpbookmarks_mybookmark_page_url is deprecated. Use cbxbookmark_mybookmark_page_url instead.'
);

// Modern replacement filter
return apply_filters( 'cbxbookmark_mybookmark_page_url', $value );

This pattern ensures:

• Old filter calls still work for existing code.
• Developers get a clear notice about the deprecation.
• All new code can adopt the modern filter.

Optional: Cleaner Variable Handling

For filters, you can assign the value first to a variable and return it after applying both deprecated and modern hooks:

$value = esc_url( $my_bookmark_page_url );

$value = apply_filters_deprecated(
    'cbxwpbookmarks_mybookmark_page_url',
    array( $value ),
    '3.2.0',
    'cbxbookmark_mybookmark_page_url',
    'The filter cbxwpbookmarks_mybookmark_page_url is deprecated. Use cbxbookmark_mybookmark_page_url instead.'
);

return apply_filters( 'cbxbookmark_mybookmark_page_url', $value );

Best Practices for Deprecating Hooks

• Always include the version number when deprecating a hook.
• Provide a replacement hook whenever possible.
• Document deprecated hooks clearly in your plugin/theme documentation.
• Use WP_DEBUG mode to test that deprecation notices appear correctly.
• Never remove a hook abruptly without providing backward compatibility.

Summary Table

Type	Function	Example
Action Hook	do_action_deprecated()	do_action_deprecated('old_hook', array($args), '3.2.0', 'new_hook');
Filter Hook	apply_filters_deprecated()	$value = apply_filters_deprecated('old_filter', array($value), '3.2.0', 'new_filter');

By following this approach, you ensure your WordPress plugins and themes stay modern, backward-compatible, and developer-friendly.

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