'error',
		'exact',
		'feed',
		'hour',
		'link_category',
		'm',
		'minute',
		'monthnum',
		'more',
		'name',
		'nav_menu',
		'nopaging',
		'offset',
		'order',
		'orderby',
		'p',
		'page',
		'page_id',
		'paged',
		'pagename',
		'pb',
		'perm',
		'post',
		'post__in',
		'post__not_in',
		'post_format',
		'post_mime_type',
		'post_status',
		'post_tag',
		'post_type',
		'posts',
		'posts_per_archive_page',
		'posts_per_page',
		'preview',
		'robots',
		's',
		'search',
		'second',
		'sentence',
		'showposts',
		'static',
		'subpost',
		'subpost_id',
		'tag',
		'tag__and',
		'tag__in',
		'tag__not_in',
		'tag_id',
		'tag_slug__and',
		'tag_slug__in',
		'taxonomy',
		'tb',
		'term',
		'type',
		'w',
		'withcomments',
		'withoutcomments',
		'year',
	);

	return in_array( $attribute_name, $reserved_terms, true );
}

/**
 * Callback for array filter to get visible only.
 *
 * @since  3.0.0
 * @param  WC_Product_Attribute $attribute Attribute data.
 * @return bool
 */
function wc_attributes_array_filter_visible( $attribute ) {
	return $attribute && is_a( $attribute, 'WC_Product_Attribute' ) && $attribute->get_visible() && ( ! $attribute->is_taxonomy() || taxonomy_exists( $attribute->get_name() ) );
}

/**
 * Callback for array filter to get variation attributes only.
 *
 * @since  3.0.0
 * @param  WC_Product_Attribute $attribute Attribute data.
 * @return bool
 */
function wc_attributes_array_filter_variation( $attribute ) {
	return $attribute && is_a( $attribute, 'WC_Product_Attribute' ) && $attribute->get_variation();
}

/**
 * Check if an attribute is included in the attributes area of a variation name.
 *
 * @since  3.0.2
 * @param  string $attribute Attribute value to check for.
 * @param  string $name      Product name to check in.
 * @return bool
 */
function wc_is_attribute_in_product_name( $attribute, $name ) {
	$is_in_name = stristr( $name, ' ' . $attribute . ',' ) || 0 === stripos( strrev( $name ), strrev( ' ' . $attribute ) );
	return apply_filters( 'woocommerce_is_attribute_in_product_name', $is_in_name, $attribute, $name );
}

/**
 * Callback for array filter to get default attributes.  Will allow for '0' string values, but regard all other
 * class PHP FALSE equivalents normally.
 *
 * @since 3.1.0
 * @param mixed $attribute Attribute being considered for exclusion from parent array.
 * @return bool
 */
function wc_array_filter_default_attributes( $attribute ) {
	return is_scalar( $attribute ) && ( ! empty( $attribute ) || '0' === $attribute );
}

/**
 * Get attribute data by ID.
 *
 * @since  3.2.0
 * @param  int $id Attribute ID.
 * @return stdClass|null
 */
function wc_get_attribute( $id ) {
	$attributes = wc_get_attribute_taxonomies();

	if ( ! isset( $attributes[ 'id:' . $id ] ) ) {
		return null;
	}

	$data                    = $attributes[ 'id:' . $id ];
	$attribute               = new stdClass();
	$attribute->id           = (int) $data->attribute_id;
	$attribute->name         = $data->attribute_label;
	$attribute->slug         = wc_attribute_taxonomy_name( $data->attribute_name );
	$attribute->type         = $data->attribute_type;
	$attribute->order_by     = $data->attribute_orderby;
	$attribute->has_archives = (bool) $data->attribute_public;
	return $attribute;
}

/**
 * Create attribute.
 *
 * @since  3.2.0
 * @param  array $args Attribute arguments {
 *     Array of attribute parameters.
 *
 *     @type int    $id           Unique identifier, used to update an attribute.
 *     @type string $name         Attribute name. Always required.
 *     @type string $slug         Attribute alphanumeric identifier.
 *     @type string $type         Type of attribute.
 *                                Core by default accepts: 'select' and 'text'.
 *                                Default to 'select'.
 *     @type string $order_by     Sort order.
 *                                Accepts: 'menu_order', 'name', 'name_num' and 'id'.
 *                                Default to 'menu_order'.
 *     @type bool   $has_archives Enable or disable attribute archives. False by default.
 * }
 * @return int|WP_Error
 */
function wc_create_attribute( $args ) {
	global $wpdb;

	$args   = wp_unslash( $args );
	$id     = ! empty( $args['id'] ) ? intval( $args['id'] ) : 0;
	$format = array( '%s', '%s', '%s', '%s', '%d' );

	// Name is required.
	if ( empty( $args['name'] ) ) {
		return new WP_Error( 'missing_attribute_name', __( 'Please, provide an attribute name.', 'woocommerce' ), array( 'status' => 400 ) );
	}

	// Set the attribute slug.
	if ( empty( $args['slug'] ) ) {
		$slug = wc_sanitize_taxonomy_name( $args['name'] );
	} else {
		$slug = preg_replace( '/^pa\_/', '', wc_sanitize_taxonomy_name( $args['slug'] ) );
	}

	// Validate slug.
	if ( strlen( $slug ) >= 28 ) {
		/* translators: %s: attribute slug */
		return new WP_Error( 'invalid_product_attribute_slug_too_long', sprintf( __( 'Slug "%s" is too long (28 characters max). Shorten it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
	} elseif ( wc_check_if_attribute_name_is_reserved( $slug ) ) {
		/* translators: %s: attribute slug */
		return new WP_Error( 'invalid_product_attribute_slug_reserved_name', sprintf( __( 'Slug "%s" is not allowed because it is a reserved term. Change it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
	} elseif ( ( 0 === $id && taxonomy_exists( wc_attribute_taxonomy_name( $slug ) ) ) || ( isset( $args['old_slug'] ) && $args['old_slug'] !== $slug && taxonomy_exists( wc_attribute_taxonomy_name( $slug ) ) ) ) {
		/* translators: %s: attribute slug */
		return new WP_Error( 'invalid_product_attribute_slug_already_exists', sprintf( __( 'Slug "%s" is already in use. Change it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
	}

	// Validate type.
	if ( empty( $args['type'] ) || ! array_key_exists( $args['type'], wc_get_attribute_types() ) ) {
		$args['type'] = 'select';
	}

	// Validate order by.
	if ( empty( $args['order_by'] ) || ! in_array( $args['order_by'], array( 'menu_order', 'name', 'name_num', 'id' ), true ) ) {
		$args['order_by'] = 'menu_order';
	}

	$data = array(
		'attribute_label'   => $args['name'],
		'attribute_name'    => $slug,
		'attribute_type'    => $args['type'],
		'attribute_orderby' => $args['order_by'],
		'attribute_public'  => isset( $args['has_archives'] ) ? (int) $args['has_archives'] : 0,
	);

	// Create or update.
	if ( 0 === $id ) {
		$results = $wpdb->insert(
			$wpdb->prefix . 'woocommerce_attribute_taxonomies',
			$data,
			$format
		);

		if ( is_wp_error( $results ) ) {
			return new WP_Error( 'cannot_create_attribute', $results->get_error_message(), array( 'status' => 400 ) );
		}

		$id = $wpdb->insert_id;

		/**
		 * Attribute added.
		 *
		 * @param int   $id   Added attribute ID.
		 * @param array $data Attribute data.
		 */
		do_action( 'woocommerce_attribute_added', $id, $data );
	} else {
		$results = $wpdb->update(
			$wpdb->prefix . 'woocommerce_attribute_taxonomies',
			$data,
			array( 'attribute_id' => $id ),
			$format,
			array( '%d' )
		);

		if ( false === $results ) {
			return new WP_Error( 'cannot_update_attribute', __( 'Could not update the attribute.', 'woocommerce' ), array( 'status' => 400 ) );
		}

		// Set old slug to check for database changes.
		$old_slug = ! empty( $args['old_slug'] ) ? wc_sanitize_taxonomy_name( $args['old_slug'] ) : $slug;

		/**
		 * Attribute updated.
		 *
		 * @param int    $id       Added attribute ID.
		 * @param array  $data     Attribute data.
		 * @param string $old_slug Attribute old name.
		 */
		do_action( 'woocommerce_attribute_updated', $id, $data, $old_slug );

		if ( $old_slug !== $slug ) {
			// Update taxonomies in the wp term taxonomy table.
			$wpdb->update(
				$wpdb->term_taxonomy,
				array( 'taxonomy' => wc_attribute_taxonomy_name( $data['attribute_name'] ) ),
				array( 'taxonomy' => 'pa_' . $old_slug )
			);

			// Update taxonomy ordering term meta.
			$wpdb->update(
				$wpdb->termmeta,
				array( 'meta_key' => 'order_pa_' . sanitize_title( $data['attribute_name'] ) ), // WPCS: slow query ok.
				array( 'meta_key' => 'order_pa_' . sanitize_title( $old_slug ) ) // WPCS: slow query ok.
			);

			// Update product attributes which use this taxonomy.
			$old_taxonomy_name = 'pa_' . $old_slug;
			$new_taxonomy_name = 'pa_' . $data['attribute_name'];
			$old_attribute_key = sanitize_title( $old_taxonomy_name ); // @see WC_Product::set_attributes().
			$new_attribute_key = sanitize_title( $new_taxonomy_name ); // @see WC_Product::set_attributes().
			$metadatas         = $wpdb->get_results(
				$wpdb->prepare(
					"SELECT post_id, meta_value FROM {$wpdb->postmeta} WHERE meta_key = '_product_attributes' AND meta_value LIKE %s",
					'%' . $wpdb->esc_like( $old_taxonomy_name ) . '%'
				),
				ARRAY_A
			);
			foreach ( $metadatas as $metadata ) {
				$product_id        = $metadata['post_id'];
				$unserialized_data = maybe_unserialize( $metadata['meta_value'] );

				if ( ! $unserialized_data || ! is_array( $unserialized_data ) || ! isset( $unserialized_data[ $old_attribute_key ] ) ) {
					continue;
				}

				$unserialized_data[ $new_attribute_key ] = $unserialized_data[ $old_attribute_key ];
				unset( $unserialized_data[ $old_attribute_key ] );
				$unserialized_data[ $new_attribute_key ]['name'] = $new_taxonomy_name;
				update_post_meta( $product_id, '_product_attributes', wp_slash( $unserialized_data ) );
			}

			// Update variations which use this taxonomy.
			$wpdb->update(
				$wpdb->postmeta,
				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $data['attribute_name'] ) ), // WPCS: slow query ok.
				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $old_slug ) ) // WPCS: slow query ok.
			);
		}
	}

	// Clear cache and flush rewrite rules.
	wp_schedule_single_event( time(), 'woocommerce_flush_rewrite_rules' );
	delete_transient( 'wc_attribute_taxonomies' );
	WC_Cache_Helper::invalidate_cache_group( 'woocommerce-attributes' );

	return $id;
}

/**
 * Update an attribute.
 *
 * For available args see wc_create_attribute().
 *
 * @since  3.2.0
 * @param  int   $id   Attribute ID.
 * @param  array $args Attribute arguments.
 * @return int|WP_Error
 */
function wc_update_attribute( $id, $args ) {
	global $wpdb;

	$attribute = wc_get_attribute( $id );

	$args['id'] = $attribute ? $attribute->id : 0;

	if ( $args['id'] && empty( $args['name'] ) ) {
		$args['name'] = $attribute->name;
	}

	$args['old_slug'] = $wpdb->get_var(
		$wpdb->prepare(
			"
				SELECT attribute_name
				FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
				WHERE attribute_id = %d
			",
			$args['id']
		)
	);

	return wc_create_attribute( $args );
}

/**
 * Delete attribute by ID.
 *
 * @since  3.2.0
 * @param  int $id Attribute ID.
 * @return bool
 */
function wc_delete_attribute( $id ) {
	global $wpdb;

	$name = $wpdb->get_var(
		$wpdb->prepare(
			"
			SELECT attribute_name
			FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
			WHERE attribute_id = %d
			",
			$id
		)
	);

	$taxonomy = wc_attribute_taxonomy_name( $name );

	/**
	 * Before deleting an attribute.
	 *
	 * @param int    $id       Attribute ID.
	 * @param string $name     Attribute name.
	 * @param string $taxonomy Attribute taxonomy name.
	 */
	do_action( 'woocommerce_before_attribute_delete', $id, $name, $taxonomy );

	if ( $name && $wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}woocommerce_attribute_taxonomies WHERE attribute_id = %d", $id ) ) ) {
		if ( taxonomy_exists( $taxonomy ) ) {
			$terms = get_terms( $taxonomy, 'orderby=name&hide_empty=0' );
			foreach ( $terms as $term ) {
				wp_delete_term( $term->term_id, $taxonomy );
			}
		}

		/**
		 * After deleting an attribute.
		 *
		 * @param int    $id       Attribute ID.
		 * @param string $name     Attribute name.
		 * @param string $taxonomy Attribute taxonomy name.
		 */
		do_action( 'woocommerce_attribute_deleted', $id, $name, $taxonomy );
		wp_schedule_single_event( time(), 'woocommerce_flush_rewrite_rules' );
		delete_transient( 'wc_attribute_taxonomies' );
		WC_Cache_Helper::invalidate_cache_group( 'woocommerce-attributes' );

		return true;
	}

	return false;
}

/**
 * Get an unprefixed product attribute name.
 *
 * @since 3.6.0
 *
 * @param  string $attribute_name Attribute name.
 * @return string
 */
function wc_attribute_taxonomy_slug( $attribute_name ) {
	$prefix      = WC_Cache_Helper::get_cache_prefix( 'woocommerce-attributes' );
	$cache_key   = $prefix . 'slug-' . $attribute_name;
	$cache_value = wp_cache_get( $cache_key, 'woocommerce-attributes' );

	if ( $cache_value ) {
		return $cache_value;
	}

	$attribute_name = wc_sanitize_taxonomy_name( $attribute_name );
	$attribute_slug = 0 === strpos( $attribute_name, 'pa_' ) ? substr( $attribute_name, 3 ) : $attribute_name;
	wp_cache_set( $cache_key, $attribute_slug, 'woocommerce-attributes' );

	return $attribute_slug;
}
<br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function wc_get_attribute_taxonomies() in /home/payon/public_html/wp-content/plugins/woocommerce/includes/class-wc-post-types.php:206
Stack trace:
#0 /home/payon/public_html/wp-includes/class-wp-hook.php(308): WC_Post_Types::register_taxonomies('')
#1 /home/payon/public_html/wp-includes/class-wp-hook.php(332): WP_Hook-&gt;apply_filters(NULL, Array)
#2 /home/payon/public_html/wp-includes/plugin.php(517): WP_Hook-&gt;do_action(Array)
#3 /home/payon/public_html/wp-settings.php(623): do_action('init')
#4 /home/payon/public_html/wp-config.php(92): require_once('/home/payon/pub...')
#5 /home/payon/public_html/wp-load.php(50): require_once('/home/payon/pub...')
#6 /home/payon/public_html/wp-blog-header.php(13): require_once('/home/payon/pub...')
#7 /home/payon/public_html/index.php(17): require('/home/payon/pub...')
#8 {main}
  thrown in <b>/home/payon/public_html/wp-content/plugins/woocommerce/includes/class-wc-post-types.php</b> on line <b>206</b><br />