filemtime() warning when enqueuing style within plugin

Question

I'm receiving the following filemtime() warning:

Warning: filemtime(): stat failed for https://testing.local/wp-content/plugins/test-social-icons/css/style.css in /app/public/wp-content/plugins/zoo-social-icons/zoo-social-icons.php on line 29

Here's how I'm enqueuing the stylesheet within my plugin:

function test_styles_scripts() {
   $dir = plugin_dir_url(__FILE__);
   wp_enqueue_style( 'test-style', $dir . 'css/style.css', array(), filemtime( $dir . 'css/style.css' ) );
}
add_action( 'wp_enqueue_scripts', 'test_styles_scripts' );

The stylesheet is correctly enqueuing. Why am I getting this warning?

Answer 1

Restating the answer from @JacobPeattie in the comments above.

filemtime() requires a path, not a URL

Therefore use plugin_dir_path(__FILE__).

The full string for properly printing the cache-busting part of the version number at the end of the asset would be filemtime( plugin_dir_path(__FILE__)

Answer 2

The filemtime() function in PHP expects a filesystem path, not a URL. However, in your code, you're passing a URL to filemtime(), which causes the stat failed warning.

To fix this issue, you need to use the correct function to get the filesystem path, which is plugin_dir_path(). This function will give you the path to the plugin directory in the filesystem, which you can then use with filemtime().

how you can fix your code:

Use plugin_dir_path() to get the filesystem path. Use plugin_dir_url() to get the URL for enqueuing the stylesheet.

Try Code

function test_styles_scripts() {
   // Get the URL of the plugin directory
   $dir_url = plugin_dir_url(__FILE__);
   
   // Get the filesystem path of the plugin directory
   $dir_path = plugin_dir_path(__FILE__);
   
   // Enqueue the stylesheet with the file modification time as the version
   wp_enqueue_style('test-style', $dir_url . 'css/style.css', array(), filemtime($dir_path . 'css/style.css'));
}
add_action('wp_enqueue_scripts', 'test_styles_scripts');