Dovecot -n (SIGFPE error on mail

# /etc/dovecot/dovecot.conf
log_timestamp: %Y-%m-%d %H:%M:%S 
protocols: imap
login_dir: /var/run/dovecot/login
login_executable: /usr/lib/dovecot/imap-login
mail_extra_groups: mail
mail_location: maildir:~/Maildir
auth default:
  passdb:
    driver: pam
  userdb:
    driver: passwd