Title: Conditional groups in Additional headers critical error
Last modified: October 11, 2023

---

# Conditional groups in Additional headers critical error

 *  Resolved [davidjt91](https://wordpress.org/support/users/davidjt91/)
 * (@davidjt91)
 * [2 years, 8 months ago](https://wordpress.org/support/topic/conditional-groups-in-additional-headers-critical-error/)
 * I’m having a problem using conditional groups in Additional headers.
 * In previous versions of this plugin I’ve used them without any issues, but now
   when saving any cotact form that has conditional groups in Additional headers,
   it gives a Critical error. It still saves and functions correctly, but the Critical
   error is making me worried.
 * For example this will give an error:
 *     ```wp-block-code
       Cc: [group]contact@mail.com,[/group]
       ```
   
 * I’ve tried both on the website that has had them for years, and in a new clean
   installation of WordPress, with the basic theme and without any other plugins,
   and it gives me the same error:
 *     ```wp-block-code
       Fatal error:  Uncaught Error: Undefined class constant 'error_invalid_mailbox_syntax' in (...)/wp-content/plugins/cf7-conditional-fields/cf7cf.php:78
       Stack trace:
       #0 (...)/wp-includes/class-wp-hook.php(310): CF7CF->wpcf7cf_config_validator_validate(Object(WPCF7_ConfigValidator))
       #1 (...)/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters('', Array)
       #2 (...)/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
       #3 (...)/wp-content/plugins/contact-form-7/includes/config-validator/validator.php(329): do_action('wpcf7_config_va...', Object(WPCF7_ConfigValidator))
       #4 (...)/wp-content/plugins/contact-form-7/admin/admin.php(249): WPCF7_ConfigValidator->validate()
       #5 (...)/wp-includes/class-wp-hook.php(308): wpcf7_load_contact_form_admin()
       #6 (...)/wp-includes/class-wp-hook.php(334): WP_Hook->a in (...)/wp-content/plugins/cf7-conditional-fields/cf7cf.php on line 78
       ```
   
 * In further testing, I’ve tried using a previous version of the main CF7 plugin(
   5.7.7) and it didn’t give an error, but after 5.8 it does.
 * Thanks in advance.
    -  This topic was modified 2 years, 8 months ago by [davidjt91](https://wordpress.org/support/users/davidjt91/).

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Author [Jules Colle](https://wordpress.org/support/users/jules-colle/)
 * (@jules-colle)
 * [2 years, 7 months ago](https://wordpress.org/support/topic/conditional-groups-in-additional-headers-critical-error/#post-17126369)
 * Thanks for bringing this to my attention. The error should be safe to ignore.
   Errors like this have always been thrown by CF7. My plugin is just suppressing
   this, because I haven’t figured out yet how to hook into the validation function.
   Should be safe to ignore, but I’ll check if I can do something about it with 
   the next update.
 *  Plugin Author [Jules Colle](https://wordpress.org/support/users/jules-colle/)
 * (@jules-colle)
 * [2 years, 6 months ago](https://wordpress.org/support/topic/conditional-groups-in-additional-headers-critical-error/#post-17238470)
 * I think this is resolved by now. Let me know if it’s not the case.

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Conditional groups in Additional headers critical error’ is closed to
new replies.

 * ![](https://ps.w.org/cf7-conditional-fields/assets/icon-256x256.png?rev=2072595)
 * [Conditional Fields for Contact Form 7](https://wordpress.org/plugins/cf7-conditional-fields/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/cf7-conditional-fields/#faq)
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 * 2 replies
 * 2 participants
 * Last reply from: [Jules Colle](https://wordpress.org/support/users/jules-colle/)
 * Last activity: [2 years, 6 months ago](https://wordpress.org/support/topic/conditional-groups-in-additional-headers-critical-error/#post-17238470)
 * Status: resolved