Hello. I have followed the instructions and still with the same error.
Fatal error: Uncaught Error: Call to undefined function MailPoet\Migrator\mb_strimwidth() in /var/www/recursos/wp-content/plugins/mailpoet/lib/Migrator/Migrator.php:90 Stack trace: #0 /var/www/recursos/wp-content/plugins/mailpoet/lib/Migrator/Migrator.php(38): MailPoet\Migrator\Migrator->getStatus() #1 /var/www/recursos/wp-content/plugins/mailpoet/lib/Config/Activator.php(78): MailPoet\Migrator\Migrator->run() #2 /var/www/recursos/wp-content/plugins/mailpoet/lib/Config/Activator.php(60): MailPoet\Config\Activator->processActivate() #3 /var/www/recursos/wp-content/plugins/mailpoet/lib/Config/Initializer.php(288): MailPoet\Config\Activator->activate() #4 /var/www/recursos/wp-includes/class-wp-hook.php(310): MailPoet\Config\Initializer->runActivator() #5 /var/www/recursos/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters() #6 /var/www/recursos/wp-includes/plugin.php(517): WP_Hook->do_action() #7 /var/www/recursos/wp-admin/plugins.php(194): do_action() #8 {main} thrown in /var/www/recursos/wp-content/plugins/mailpoet/lib/Migrator/Migrator.php on line 90
