How to click on alert message using nightwatch.js?

I use nodejs + nightwatch + chrome driver to run my e2e tests and got problem: i can't accept alert massage on page. In documentation for nightwatch i see information for Selenium Protocol to do this. But, when i try something like this:

request.post('/session/'+session+'/accept_alert', function (error, response, body) {
    console.log(error)
})

I get error:

[Error: Invalid URI "/session/9bb486d4-5e30-40bb-a236-b6921dd0f583/accept_alert"]

Can i accept alert from nightwatch? Or why i get this err? How to fix?