PHP Error pops up via Query Monitor

I installed the Query Monitor plugin where it monitors, among other things, page errors. I noticed that the plugin indicates errors:

Message:

• rmdir(/public_html/wp-content/uploads/wp_dndcf7_uploads/wpcf7-files/): Directory not empty

Location:

1. wp-content/plugins/drag-and-drop-multiple-file-upload-contact-form-7/inc/dnd-upload-cf7.php:273
2. rmdir()
   wp-content/plugins/drag-and-drop-multiple-file-upload-contact-form-7/inc/dnd-upload-cf7.php:273
3. dnd_cf7_auto_clean_dir()
   wp-includes/class-wp-hook.php:322
4. do_action('template_redirect')
   wp-includes/template-loader.php:13

Component:

• Plugin: drag-and-drop-multiple-file-upload-contact-form-7

What could be causing these errors to appear?