Jayne

Please ignore the above!
Sorry – it’s got some errors in it – will work on fixing it and post back

Here’s a link to an even slicker solution, and it means you don’t have to upload a default image to your themes folder – you can just use the ID of one of your already uploaded images

Creating Default WordPress Post Thumbnail or Featured Image

Here’s a link for how to add images to posts that don’t have any featured image set – you can add a link to the file via your functions.php file.

How to define a default post thumbnail

Hope this helps

I am not using this plugin but came across a similar error on my own custom autoset featured image, which I have modified from here.

I have included a few extra lines which means you don’t get the debug errors on posts that haven’t been created yet e.g. on new-post.php and new-page.php admin screens

The following may help you:

Create a new file called and name it something like featured-image.php and save somewhere in your themes folder

Then include a reference to if from your functions.php file e.g. (replace /inc/ with your path to the file)

require get_template_directory() . '/inc/featured-image.php';

Then in the featured-image.php file drop the following code

/**
 * Autoset featured image to first image in post if not specifically defined
 */
add_action('the_post', 'your_theme_autoset_featured_image');
add_action('save_post', 'your_theme_autoset_featured_image');
add_action('draft_to_publish', 'your_theme_autoset_featured_image');
add_action('new_to_publish', 'your_theme_autoset_featured_image');
add_action('pending_to_publish', 'your_theme_autoset_featured_image');
add_action('future_to_publish', 'your_theme_autoset_featured_image');
function your_theme_autoset_featured_image() {

		//checks for thumbnail - it does not use the global post ID because we haven't created a post yet!
		if ( !has_post_thumbnail() ){

			// if post does not have a thumbnail then do nothing!!
			}

		else {

			// set globals for the function
			global $post;
			$already_has_thumb = has_post_thumbnail($post->ID);
			$screen = get_current_screen();

	/*
	* checks that you are not on add a new post or add new page screen, so it is not looking for empty objects and thus returning no debug errors! Yay!
	*/
		// check for thumb and what admin page you are on
		if (!$already_has_thumb && $screen->base !== '-new.php')  {

			$attached_image = get_children( "post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );

			if ($attached_image) {
				foreach ($attached_image as $attachment_id => $attachment) {
				set_post_thumbnail($post->ID, $attachment_id);
				}
			}

		}
	}
}

The crucial bits in the code above are

if ( !has_post_thumbnail() ){
// if post does not have a thumbnail then do nothing!!
}

and

if (!$already_has_thumb && $screen->base !== '-new.php')  {
//original code
}

You might be able to modify the plugin php files with the extra bits Hope this helps