mailworm on "[Plugin: iThemes Security (formerly Better WP Security)] Strong passwords - PHP error when saving user"

I am getting the following error, when forcing strong passwords:

Warning: Cannot modify header information - headers already sent by (output started at .../plugins/better-wp-security/modules/free/strong-passwords/class-itsec-strong-passwords.php:80) in .../wp-includes/pluggable.php on line 896

For now I disabled this feature.

https://wordpress.org/plugins/better-wp-security/