I am trying to change the stylesheet file version using the filemtime() function with the wp_enqueue_style with the following snippet

function pro_styles()
wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() .'/child-style.css', array(), filemtime(get_stylesheet_directory_uri() .'/child-style.css'), 'all' );

add_action( 'wp_enqueue_scripts', 'pro_styles' );

but it is throwing a warning

Warning: filemtime(): stat failed for.....

While i am sure that the file exists

2 Answers 2


It's because you're retrieving it via URL, but filemtime() requires a path. Use get_stylesheet_directory() instead. That returns a path:

function pro_styles()
wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() .'/child-style.css', array(), filemtime(get_stylesheet_directory() .'/child-style.css'), 'all' );

add_action( 'wp_enqueue_scripts', 'pro_styles' );

Just to expand on Jacob Peattie Answer for people that have CSS file in a custom plugin, you can use

filemtime( plugin_dir_path(dirname(__FILE__)).'plugin-folder/css-file-path.css' )
  • 1
    great, it works!
    – Iggy
    Commented Jun 25, 2020 at 15:08
  • Good find! Further, if the file is in your own same plugin folder, filemtime(plugin_dir_path(__FILE__) . 'css-file-path.css') suffices.
    – Sygmoral
    Commented May 17, 2023 at 12:54

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