Title: PHP8 Error
Last modified: July 26, 2021

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# PHP8 Error

 *  [WebCodePoet](https://wordpress.org/support/users/senjoralfonso/)
 * (@senjoralfonso)
 * [4 years, 10 months ago](https://wordpress.org/support/topic/php8-error-3/)
 * Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($function)
   must be a valid callback, class InboxWebmail_Helper_Upgrade does not have a method“
   upgrade” in /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php:
   303 Stack trace: #0 /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-
   hook.php(327): WP_Hook->apply_filters() #1 /var/www/vhosts/example.com/httpdocs/
   wp-includes/plugin.php(470): WP_Hook->do_action() #2 /var/www/vhosts/example.
   com/httpdocs/wp-admin/plugins.php(193): do_action() #3 {main} thrown in /var/
   www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php on line 303

The topic ‘PHP8 Error’ is closed to new replies.

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 * 0 replies
 * 1 participant
 * Last reply from: [WebCodePoet](https://wordpress.org/support/users/senjoralfonso/)
 * Last activity: [4 years, 10 months ago](https://wordpress.org/support/topic/php8-error-3/)
 * Status: not resolved