{"id":18997528,"date":"2026-08-19T15:36:47","date_gmt":"2026-08-19T15:36:47","guid":{"rendered":"https:\/\/wordpress.org\/support\/topic\/bug-report-undefined-variable-output-php-warning-in-su_feed-shortcode\/"},"modified":"2026-08-19T16:40:42","modified_gmt":"2026-08-19T16:40:42","slug":"bug-report-undefined-variable-output-php-warning-in-su_feed-shortcode","status":"publish","type":"topic","link":"https:\/\/wordpress.org\/support\/topic\/bug-report-undefined-variable-output-php-warning-in-su_feed-shortcode\/","title":{"rendered":"Bug Report: “Undefined variable $output” PHP warning in [su_feed] shortcode"},"content":{"rendered":"\n

Bug Report: “Undefined variable $output” PHP warning in [su_feed] shortcode<\/strong><\/p>\n\n\n\n

Plugin: Shortcodes Ultimate (shortcodes-ultimate)
Version: 7.8.4 (latest as of 2026-08-19)
WordPress: 7.0.4
PHP: 8.5.4
Status: Active Summary<\/p>\n\n\n\n

Using the [su_feed] shortcode on a page emits a PHP warning on every render:<\/p>\n\n\n\n

PHP Warning: Undefined variable $output in\n...\/shortcodes-ultimate\/includes\/shortcodes\/feed.php on line 83<\/code><\/pre>\n\n\n\n
The shortcode still outputs the feed correctly \u2014 this is a log-noise warning,
not a visible break \u2014 but it fires on every page load that includes feed items,
which quickly floods the PHP-FPM\/nginx error log. Steps to reproduce<\/p>\n\n\n\n
    \n
  1. Install Shortcodes Ultimate 7.8.4 on WordPress 7.0.4 with PHP 8.x.<\/li>\n\n\n\n
  2. Add a page containing a feed shortcode with items available, e.g.:<\/li>\n<\/ol>\n\n\n\n
    [su_feed url=”https:\/\/example.com\/category\/news\/feed\/” limit=”-1″]<\/p>\n\n\n\n
    (Also reproduced with limit=”3″. The site uses the compatibility prefix
    option “su_”, so the tag is [su_feed].)<\/p>\n\n\n\n
    Load the page. The warning is emitted once per shortcode render. Root cause<\/p>\n\n\n\n
    In includes\/shortcodes\/feed.php, the variable $output is used with the
    concatenating assignment operator inside the foreach loop, but is never
    initialized before the loop:<\/p>\n\n\n\n
    foreach ( $items as $item ) {\n\n    $output .= sprintf(\n        '<li><a href=\"%s\" target=\"_%s\" title=\"%s\">%s<\/a><\/li>',\n        esc_url( $item->get_permalink() ),\n        sanitize_key( $atts['target'] ),\n        esc_attr( $item->get_description() ),\n        wp_kses_post( $item->get_title() )\n    );\n\n}\n\nreturn sprintf(\n    '<ul class=\"su-feed%s\">%s<\/ul>',\n    esc_attr( su_get_css_class( $atts ) ),\n    $output\n);<\/code><\/pre>\n\n\n\n
    On the first loop iteration, $output is undefined, so PHP 8 emits
    “Undefined variable $output”. (PHP reports the warning at the line where the
    sprintf argument list ends \u2014 line 83 in 7.8.4 \u2014 which made it slightly
    confusing to track down at first.) Suggested fix (one line)<\/p>\n\n\n\n
    Initialize $output before the loop:<\/p>\n\n\n\n
    $output = '';\n\nforeach ( $items as $item ) {\n    ...<\/code><\/pre>\n\n\n\n
    (If the early-return guard “if ( ! count( $items ) )” were ever removed, the
    same initialization would also protect the return statement below the loop.) Workaround<\/p>\n\n\n\n
    For anyone hitting this before the fix ships: a must-use plugin that
    re-registers the “feed” shortcode with a corrected callback (remove_shortcode +
    add_shortcode on init, priority 50 \u2014 after SU registers at priority 40)
    removes the warning without modifying plugin files. 

    Notes<\/strong><\/p>\n\n\n\n
      \n
    • Warning is cosmetic: feed HTML output is correct.<\/li>\n\n\n\n
    • Occurs on PHP 8.x; will also affect PHP 9 when release notes inevitably
      promote undefined-variable notices to errors (PHP 8.0+ already emits the
      warning under error_reporting(E_ALL)).<\/li>\n\n\n\n
    • Only affects the free “feed” shortcode; other shortcodes were not checked
      for the same pattern.<\/li>\n<\/ul>\n","protected":false},"template":"","class_list":["post-18997528","topic","type-topic","status-publish","hentry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/topic\/18997528","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/topic"}],"about":[{"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":1,"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/topic\/18997528\/revisions"}],"predecessor-version":[{"id":18997533,"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/topic\/18997528\/revisions\/18997533"}],"wp:attachment":[{"href":"https:\/\/wordpress.org\/support\/wp-json\/wp\/v2\/media?parent=18997528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}