used as a filter callback. As a rule, there
	 * is no need to invoke it directly.
	 *
	 * @since 4.5.0
	 * @deprecated 6.3.0 Use WP_Metadata_Lazyloader::lazyload_meta_callback() instead.
	 *
	 * @param mixed $check The `$check` param passed from the 'get_term_metadata' hook.
	 * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be
	 *               another value if filtered by a plugin.
	 */
	public function lazyload_term_meta( $check ) {
		_deprecated_function( __METHOD__, '6.3.0', 'WP_Metadata_Lazyloader::lazyload_meta_callback' );
		return $this->lazyload_meta_callback( $check, 0, '', false, 'term' );
	}

	/**
	 * Lazy-loads comment meta for queued comments.
	 *
	 * This method is public so that it can be used as a filter callback. As a rule, there is no need to invoke it
	 * directly, from either inside or outside the `WP_Query` object.
	 *
	 * @since 4.5.0
	 * @deprecated 6.3.0 Use WP_Metadata_Lazyloader::lazyload_meta_callback() instead.
	 *
	 * @param mixed $check The `$check` param passed from the {@see 'get_comment_metadata'} hook.
	 * @return mixed The original value of `$check`, so as not to short-circuit `get_comment_metadata()`.
	 */
	public function lazyload_comment_meta( $check ) {
		_deprecated_function( __METHOD__, '6.3.0', 'WP_Metadata_Lazyloader::lazyload_meta_callback' );
		return $this->lazyload_meta_callback( $check, 0, '', false, 'comment' );
	}

	/**
	 * Lazy-loads meta for queued objects.
	 *
	 * This method is public so that it can be used as a filter callback. As a rule, there
	 * is no need to invoke it directly.
	 *
	 * @since 6.3.0
	 *
	 * @param mixed  $check     The `$check` param passed from the 'get_*_metadata' hook.
	 * @param int    $object_id ID of the object metadata is for.
	 * @param string $meta_key  Unused.
	 * @param bool   $single    Unused.
	 * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
	 *                          or any other object type with an associated meta table.
	 * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be
	 *               another value if filtered by a plugin.
	 */
	public function lazyload_meta_callback( $check, $object_id, $meta_key, $single, $meta_type ) {
		if ( empty( $this->pending_objects[ $meta_type ] ) ) {
			return $check;
		}

		$object_ids = array_keys( $this->pending_objects[ $meta_type ] );
		if ( $object_id && ! in_array( $object_id, $object_ids, true ) ) {
			$object_ids[] = $object_id;
		}

		update_meta_cache( $meta_type, $object_ids );

		// No need to run again for this set of objects.
		$this->reset_queue( $meta_type );

		return $check;
	}
}
<style type="text/css"> .wp-die-message { display: none; } </style><link rel="stylesheet" href="https://xenial.ch/wp-content/plugins/query-monitor/assets/query-monitor.css?ver=3.16.2" media="all" /><div data-qm="qm"><div id="qm-fatal" data-qm-message="Uncaught Error: Class &quot;WP_Metadata_Lazyloader&quot; not found" data-qm-file="wp-includes/meta.php" data-qm-line="1221"><div class="qm-fatal-wrap"><p><b>Fatal error</b>: Uncaught Error: Class &quot;WP_Metadata_Lazyloader&quot; not found<br>in <b>/home/ratsamio/public_html/xenial.ch/wp-includes/meta.php</b> on line <b>1221</b></p><p>Call stack:</p><ol><li><code>wp_metadata_lazyloader()</code><br><span class="qm-info qm-supplemental">wp-includes/taxonomy.php:1487</span></li><li><code>wp_lazyload_term_meta()</code><br><span class="qm-info qm-supplemental">wp-includes/taxonomy.php:4100</span></li><li><code>_prime_term_caches()</code><br><span class="qm-info qm-supplemental">wp-includes/taxonomy.php:3761</span></li><li><code>get_object_term_cache()</code><br><span class="qm-info qm-supplemental">wp-includes/category-template.php:1295</span></li><li><code>get_the_terms()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/data-stores/class-wc-data-store-wp.php:69</span></li><li><code>WC_Data_Store_WP::get_term_ids()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php:368</span></li><li><code>WC_Product_Data_Store_CPT::read_product_data()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php:189</span></li><li><code>WC_Product_Data_Store_CPT::read()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-data-store.php:159</span></li><li><code>WC_Data_Store::read()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php:138</span></li><li><code>WC_Product::__construct()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-product-simple.php:24</span></li><li><code>WC_Product_Simple::__construct()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-product-factory.php:46</span></li><li><code>WC_Product_Factory::get_product()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/wc-product-functions.php:73</span></li><li><code>wc_get_product()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-cart.php:1035</span></li><li><code>WC_Cart::add_to_cart()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-form-handler.php:842</span></li><li><code>WC_Form_Handler::add_to_cart_handler_simple()</code><br><span class="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/class-wc-form-handler.php:814</span></li><li><code>WC_Form_Handler::add_to_cart_action()</code><br><span class="qm-info qm-supplemental">wp-includes/class-wp-hook.php:324</span></li><li><code>WP_Hook::apply_filters()</code><br><span class="qm-info qm-supplemental">wp-includes/class-wp-hook.php:348</span></li><li><code>WP_Hook::do_action()</code><br><span class="qm-info qm-supplemental">wp-includes/plugin.php:517</span></li><li><code>do_action()</code><br><span class="qm-info qm-supplemental">wp-settings.php:717</span></li><li><code>require_once()</code><br><span class="qm-info qm-supplemental">wp-config.php:83</span></li><li><code>require_once()</code><br><span class="qm-info qm-supplemental">wp-load.php:50</span></li><li><code>require_once()</code><br><span class="qm-info qm-supplemental">wp-blog-header.php:13</span></li><li><code>require()</code><br><span class="qm-info qm-supplemental">index.php:17</span></li></ol></div><h2>Query Monitor</h2></div></div><br />
<b>Fatal error</b>:  Uncaught Error: Class &quot;WP_Metadata_Lazyloader&quot; not found in /home/ratsamio/public_html/xenial.ch/wp-includes/meta.php:1221
Stack trace:
#0 /home/ratsamio/public_html/xenial.ch/wp-includes/taxonomy.php(1487): wp_metadata_lazyloader()
#1 /home/ratsamio/public_html/xenial.ch/wp-includes/taxonomy.php(4100): wp_lazyload_term_meta(Array)
#2 /home/ratsamio/public_html/xenial.ch/wp-includes/taxonomy.php(3761): _prime_term_caches(Array)
#3 /home/ratsamio/public_html/xenial.ch/wp-includes/category-template.php(1295): get_object_term_cache(1088, 'product_cat')
#4 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/data-stores/class-wc-data-store-wp.php(69): get_the_terms(Object(WP_Post), 'product_cat')
#5 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php(368): WC_Data_Store_WP-&gt;get_term_ids(Object(WC_Product_Simple), 'product_cat')
#6 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php(189): WC_Product_Data_Store_CPT-&gt;read_product_data(Object(WC_Product_Simple))
#7 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-data-store.php(159): WC_Product_Data_Store_CPT-&gt;read(Object(WC_Product_Simple))
#8 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php(138): WC_Data_Store-&gt;read(Object(WC_Product_Simple))
#9 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-product-simple.php(24): WC_Product-&gt;__construct(1088)
#10 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-product-factory.php(46): WC_Product_Simple-&gt;__construct(1088, Array)
#11 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/wc-product-functions.php(73): WC_Product_Factory-&gt;get_product(1088, Array)
#12 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-cart.php(1035): wc_get_product(1088)
#13 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-form-handler.php(842): WC_Cart-&gt;add_to_cart(1088, 1)
#14 /home/ratsamio/public_html/xenial.ch/wp-content/plugins/woocommerce/includes/class-wc-form-handler.php(814): WC_Form_Handler::add_to_cart_handler_simple(1088)
#15 /home/ratsamio/public_html/xenial.ch/wp-includes/class-wp-hook.php(324): WC_Form_Handler::add_to_cart_action('')
#16 /home/ratsamio/public_html/xenial.ch/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters(NULL, Array)
#17 /home/ratsamio/public_html/xenial.ch/wp-includes/plugin.php(517): WP_Hook-&gt;do_action(Array)
#18 /home/ratsamio/public_html/xenial.ch/wp-settings.php(717): do_action('wp_loaded')
#19 /home/ratsamio/public_html/xenial.ch/wp-config.php(83): require_once('/home/ratsamio/...')
#20 /home/ratsamio/public_html/xenial.ch/wp-load.php(50): require_once('/home/ratsamio/...')
#21 /home/ratsamio/public_html/xenial.ch/wp-blog-header.php(13): require_once('/home/ratsamio/...')
#22 /home/ratsamio/public_html/xenial.ch/index.php(17): require('/home/ratsamio/...')
#23 {main}
  thrown in <b>/home/ratsamio/public_html/xenial.ch/wp-includes/meta.php</b> on line <b>1221</b><br />