UnexpectedTypeException: Expected argument of type "string"

Error encounted when saving new field

Symfony\Component\Validator\Exception\UnexpectedTypeException: Expected argument of type "string", "array" given in Symfony\Component\Validator\Constraints\LengthValidator->validate() (line 37 of /var/www/domain.com/vendor/symfony/validator/Constraints/LengthValidator.php).