Ninja Forms Merge Tag Incompatibility

Our site uses a ‘handl_landing_page’ merge tag that sends which landing page the user submitted the form on to our API. We noticed recently that our forms will not submit with the most recent version of the Ninja-Forms Plugin. After some investigation we could see that the issue was caused by the handl merge tags returning the wrong type.

TypeError: NF_Abstracts_MergeTags::extractCallback(): Return value must be of type string, Closure returned in \/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/Abstracts\/MergeTags.php:178\nStack trace:\n#0 \/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/Abstracts\/MergeTags.php(114): NF_Abstracts_MergeTags->extractCallback(Array, Array)\n#1 \/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/Abstracts\/MergeTags.php(100): NF_Abstracts_MergeTags->replace(‘

\/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/Abstracts\/MergeTags.php(80): NF_Abstracts_MergeTags->replace(Array)\n#3 \/var\/www\/wordpress\/www\/wp-includes\/class-wp-hook.php(326): NF_Abstracts_MergeTags->action_replace(Array)\n#4 \/var\/www\/wordpress\/www\/wp-includes\/plugin.php(205): WP_Hook->apply_filters(Array, Array)\n#5 \/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/AJAX\/Controllers\/Submission.php(488): apply_filters(‘ninja_forms_run…’, Array, ’18 ‘, 83, Array)\n#6 \/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/AJAX\/Controllers\/Submission.php(146): NF_AJAX_Controllers_Submission->process()\n#7 \/var\/www\/wordpress\/www\/wp-includes\/class-wp-hook.php(324): NF_AJAX_Controllers_Submission->submit(”)\n#8 \/var\/www\/wordpress\/www\/wp-includes\/class-wp-hook.php(348): WP_Hook->apply_filters(”, Array)\n#9 \/var\/www\/wordpress\/www\/wp-includes\/plugin.php(517): WP_Hook->do_action(Array)\n#10 \/var\/www\/wordpress\/www\/wp-admin\/admin-ajax.php(207): do_action(‘wp_ajax_nopriv_…’)\n#11 {main}\n thrown”,”file”:”\/var\/www\/wordpress\/www\/wp-content\/plugins\/ninja-forms\/includes\/Abstracts\/MergeTags.php”,”line”:178}},”debug”:[]}

Are you guys working on a compatibility update?