Problem with post ajax request

$$(document).on('click', '.er-submit', function () {

url: Url,
method: 'POST',
crossDomain: true,
success: function (data) {
error: function () {

having problem with this request console gives 400 (Bad Request)
same on v2 framework
have an idea?
Проблема с POST запросами
консоль выдает 400 (bad request)
куда капать?

There is no such API in v2

It’s v1 app. (Started long time ago, tried to migrate to v2 version, but failed for reasons I posted here)
There for I found reason not in f7 but in my server part yii2 protected via token which have to be included in post request.
Thanks for answering.
Is it possible to look through my other questions?