express does not set cookies in Production but they are visible in respoonse tab - express

Question

II have an exppress app witch works correctly in dev.
However, when i do try to set cookies in prod, cookies are visible in network tab, but do not present in the browser.
I did a research and i think i covered most common problems, still cookies are not set
You may see my express app
I do add express configuration file, which i post here as well
const app = require("express")();
require("./config/express")(app);
app.disable("x-powered-by");
app.use((req, res, next) => {
res.setHeader("Access-Control-Allow-Origin", "example.com");
res.setHeader("Access-Control-Allow-Methods", "POST,GET,OPTIONS");
res.setHeader("Access-Control-Allow-Headers", "*");
res.setHeader("Access-Control-Allow-Credentials", true);
res.setHeader(
"Access-Control-Allow-Headers",
"Origin, X-Requested-With, Content-Type, Accept"
);
if (req.method === "OPTIONS") {
// return res.sendStatus(200);
}
next();
});
//express config.js
const express = require("express");
const path = require("path");
const cookieParser = require("cookie-parser");
const bodyParser = require("body-parser");
const jwt = require("express-jwt");
const jwks = require("jwks-rsa");
const cookieSecret =
process.env.COOKIESECRET ||
"aabbcc";
// const { errorHandler } = require('../utils')
const expressSession = require("express-session");
const config = require("../config/config");
const helmet = require("helmet");
const morgan = require("morgan");
app.use(express.json());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true, limit: "50mb" }));
app.use(cookieParser()); // TRY to use it with secret as in the __express.js file
app.use(express.static("uploads"));
app.use(express.static(path.join(__dirname, "static")));
app.use(express.static(path.resolve(__basedir, "static")));
app.use("/static/uploads", express.static("static/uploads"));
app.use("/files", express.static("files"));
app.use(helmet());
app.use(morgan("combined"));
// app.use(errorHandler(err, req, res, next));
app.use(
expressSession({
secret:
"aabbcc",
resave: false,
saveUninitialized: true, cookies,
cookie: { secure: true, sameSite: "none", domain: 'example.com' },
})
);
app.set("trust proxy", 1);
};
const expiryDate = new Date(Date.now() + 60 * 60 * 1000);
res.cookie(authCookieName, token, {
expires: expiryDate,
httpOnly: true,
secure: true,
domain: "example.com",
});
res.cookie(secondCookieName, secondToken, {
expires: expiryDate,
httpOnly: true,
secure: true,
domain: "example.com",
});
res.status(200).send(user).end();
return;

Answer 1

After some research, it appeared, that this is the problem here
This Set-Cookie was blocked because its Domain attribute is invalid with regards to the current host URL
This is seen as message in the response-headers.
But i do set all domains correcty. I tried with https as well as without it
Does any ever had the same problems?
PS : Both Front end and back end run on subdomains of a main domain
backend.maindomain.com - my backend
frontend.maindomain.com - my frontend
maindomain.com - landing page from witch you are rediirected to the app front end if you want to use it

Answer 2

Solved!
It appears you need to set the main domain name as domain and cookies are being set on each subdomain