Can't delete the Featured Image once established

?? for sure no ??
I had tested the plugin up to the latest ver of WP so can you tell me what is the ver of your WP ?

Yes sure… it is the latest version 3.9.1

the problem is in $ attachment_id = z_get_attachment_id_by_url ($ taxonomy_image_url); (line 183) that returns an id although $ taxonomy_image_url is empty.

I solved it:

$taxonomy_image_url = get_option('z_taxonomy_image'.$term_id);

    if(!empty($taxonomy_image_url)) {
		 $attachment_id = z_get_attachment_id_by_url($taxonomy_image_url);
    	if (empty($size))
    		$size = 'full';
    	$taxonomy_image_url = wp_get_attachment_image_src($attachment_id, $size);
	    $taxonomy_image_url = $taxonomy_image_url[0];
    }

great plugin!

compared to my code which used advanced custom fields to obtain image on taxonomies, I have saved a lot of query with categories images!

WOW!
Now it works, thank you so much, you people are great!!!

Great that it works ??
And Thanks so much fburatti, I updated the plugin today