headers-token.js

var token = localStorage.getItem('my_tkn');

var httpHeaders;

//'x-access-token': token
//'Authorization' : token
if(token){
  httpHeaders = { 
    'Content-Type' : 'application/x-www-form-urlencoded', 
    'Accept' : 'application/json',
    'x-access-token' : token
  };
} else {
  httpHeaders = { 
    'Content-Type' : 'application/x-www-form-urlencoded', 
    'Accept' : 'application/json'
  };
}


/*
httpHeaders = { 
  'Content-Type' : 'application/x-www-form-urlencoded', 
  'Accept' : 'application/json'
};
*/

let options = {
  method: 'post',
  body: urlEncodedData // login and password
};

options.headers = new Headers(httpHeaders);

const response = yield call(fetch, `http://mysite.com/${path}`, options);

This way the server rejects the HTTP request as malformed. But when I do just like this

httpHeaders = { 
  'Content-Type' : 'application/x-www-form-urlencoded', 
  'Accept' : 'application/json'
};

it works just fine