Remove product thumbnail IDs from galleries.

gistfile1.txt

/*
 * Removes the product's thumbnail from the gallery if it's set in both. Useful after the Woo 3.0 update as the system now automatically add the image to the gallery.
 * Drop this snippet in functions.php, reload the page, then delete the function.
 */


add_action( 'init', 'remove_duplicate_gallery_images' );
function remove_duplicate_gallery_images() {
	
	// Get the products.
	$args = array( 'post_type' => 'product', 'posts_per_page' => -1 );
	$products = get_posts( $args );

	// Loop 'em.
	foreach ( $products as $product ) {

		// Get the product object.
		$_product = wc_get_product( $product->ID );

		// Get the image IDs.
		$thumbnail = get_post_thumbnail_id( $_product->get_id() );
		$gallery = $_product->get_gallery_image_ids();

		// Ignore empty galleries.
		if ( empty( $gallery ) ) {
			continue;
		}

		// Check if the thumbnail ID is in the gallery.
		if ( ( $key = array_search( intval( $thumbnail ), $gallery ) ) !== false ) {

			// If so, remove it and update the product.
			unset( $gallery[$key] );
			$_product->set_gallery_image_ids( $gallery );
			$_product->save();
		}
	}
}