<ul><li>Root cause: update.menudetails.php had bare $_POST access on all switch cases — specifically $_POST["menu_meta_robot"] throws Undefined index when no checkboxes are checked (unchecked boxes are omitted from POST entirely). PHP warning injected before echo 200, making response "&lt;br&gt;Warning...200" which != "200" in custom.js strict compare → "Unknown Error" swal.</li><li>Fixed all $_POST accesses across all switch cases with ?? null-coalescing: menuName, pageDesc, inpiconImage, icon_color, menu_meta_robot (now json_encode($_POST["menu_meta_robot"] ?? [])), all metadata fields, header, sitemap, activate, display_menu, multisite, banner.</li><li>Added ob_start() at top of update.menudetails.php to capture any stray PHP output; any captured warnings are prepended to response for console debug visibility and also logged via error_log.</li><li>Added error_reporting(E_ALL) + ini_set display_errors=1 to update.menudetails.php for debug.</li><li>Fixed details.php metadata fields: meta_title, meta_description, meta_keywords, meta_multimedia, meta_icon, Menu, MenuDesc — all unguarded $siteConfigMenuResult accesses now use ?? "".</li></ul>