Invalid header value contains a newline not followed by whitespace: 
status: 302 found
location: http://localhost/
##</code><code>##

    my $set_username = $q->cookie(
      -name => "user_name",
      -value => $user_name,
      -expires => "+1d",
      );

    my $set_session = $q->cookie(
      -name => "session",
      -value => $secret,
      -expires => "+1d",
      );

    print $q->header( -cookie => [ $set_session, $set_username ],
$q->redirect("http://localhost/"));