Just re-opening as this issue is years old but hasn't been fixed even in version 7.0 - see #259
Symfony\Component\Mime\Header\Headers::addTextHeader(): Argument #2 ($value) must be of type string, null given, called in /var/www/laravel/releases/20260119_094037/vendor/dacastro4/laravel-gmail/src/Traits/Replyable.php on line 361
Just re-opening as this issue is years old but hasn't been fixed even in version 7.0 - see #259
Symfony\Component\Mime\Header\Headers::addTextHeader(): Argument #2 ($value) must be of type string, null given, called in /var/www/laravel/releases/20260119_094037/vendor/dacastro4/laravel-gmail/src/Traits/Replyable.php on line 361