error update form 4.3.7 to 4.4

i update to 4.4 , codeigniter 4.4 info message: "Fatal error: Uncaught Error: Undefined constant "CodeIgniter\ENVIRONMENT" in H:\HELPER\SERVER\htdocs\ciall\ci4\ci43\vendor\codeigniter4\framework\system\CodeIgniter.php on line 581"

protected function bootstrapEnvironment()
{
if (is_file(APPPATH . 'Config/Boot/' . ENVIRONMENT . '.php')) {
require_once APPPATH . 'Config/Boot/' . ENVIRONMENT . '.php'; line 581
} else {
// @codeCoverageIgnoreStart
header('HTTP/1.1 503 Service Unavailable.', true, 503);
echo 'The application environment is not set correctly.';

exit(EXIT_ERROR); // EXIT_ERROR
// @codeCoverageIgnoreEnd
}
}

how to fix it
thank you for helping