Title: PHP Error in includes/class-core.php:775 PHP 8.1
Last modified: October 26, 2022

---

# PHP Error in includes/class-core.php:775 PHP 8.1

 *  [amapparat](https://wordpress.org/support/users/amapparat/)
 * (@amapparat)
 * [3 years, 7 months ago](https://wordpress.org/support/topic/php-error-in-includes-class-core-php775-php-8-1/)
 * There is an PHP error in plugins/wp-advanced-math-captcha/includes/class-core.
   php on Line 775
 * `Uncaught TypeError: array_key_exists(): Argument #2 ($array) must be of type
   array, null`
 * which orrurs when `Math_Captcha()->cookie_session->session_ids['multi']` is empty.
 * I locally fixed it by checking the array first:
 *     ```
       if(is_array(Math_Captcha()->cookie_session->session_ids['multi'])){
       …
       }
       ```
   

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

 *  [jbt-csm](https://wordpress.org/support/users/jbt-csm/)
 * (@jbt-csm)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-error-in-includes-class-core-php775-php-8-1/#post-16354678)
 * Cool. No fatal error anymore in debug.log …
   Thanks for this!!
 *  [jbt-csm](https://wordpress.org/support/users/jbt-csm/)
 * (@jbt-csm)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-error-in-includes-class-core-php775-php-8-1/#post-16354725)
 * Just wanted to add, that for PHP 8.1… another change is nescessary:
   wp-math-captcha.
   php, line 86: change ‘private function __wakeup() {}’ to ‘public function __wakeup(){}’

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

The topic ‘PHP Error in includes/class-core.php:775 PHP 8.1’ is closed to new replies.

 * ![](https://s.w.org/plugins/geopattern-icon/wp-advanced-math-captcha_cce2f3.svg)
 * [WP Advanced Math Captcha](https://wordpress.org/plugins/wp-advanced-math-captcha/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-advanced-math-captcha/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-advanced-math-captcha/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-advanced-math-captcha/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-advanced-math-captcha/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wp-advanced-math-captcha/reviews/)

 * 4 replies
 * 2 participants
 * Last reply from: [jbt-csm](https://wordpress.org/support/users/jbt-csm/)
 * Last activity: [3 years, 4 months ago](https://wordpress.org/support/topic/php-error-in-includes-class-core-php775-php-8-1/#post-16354725)
 * Status: not resolved