Fatal error: Uncaught Error: Class 'WP_Upgrader_Skin' not found in /home/refref/public_html/wp-post-to-pdf-enhanced-cache-20250414195233/wp-post-to-pdf-enhanced-cache/includes/class-theme-upgrader-skin.php:18 Stack trace: #0 {main} thrown in /home/refref/public_html/wp-post-to-pdf-enhanced-cache-20250414195233/wp-post-to-pdf-enhanced-cache/includes/class-theme-upgrader-skin.php on line 18