Recently i have deployed both node/express api and client(Nextjs 14.1.0) to vercel everything works fine except cookies. In some cases i am getting cookies but they are just temporary when i refresh the page everything gone and other cases i am getting this warning(below) about the domain.

“The attempt to set a cookie via a Set-Cookie was blocked because its domain attribute was invalid”

Even i set domain in cookies like below but still no success

res.cookie("refreshToken", refreshToken, {
    maxAge: 15 * 24 * 60 * 60 * 1000,
    sameSite: "none",
    httpOnly: true,
    secure: true,
    partitioned: true,
    domain: ".mern-nextjs-ecommerce.vercel.app"
  });
  res.cookie("accessToken", accessToken, {
    maxAge: 15 * 24 * 60 * 60 * 1000,
    sameSite: "none",
    httpOnly: true,
    secure: true,
    partitioned: true,
domain: ".mern-nextjs-ecommerce.vercel.app"
  });

Signin Code

export const signIn = TryCatch(async (req, res, next) => {
  const { email, password } = req.body;

  const user = await User.findOne({ email });
  if (!user) return next(new ErrorHandler("Invalid credentials", 400));

  const isMatched = await user.comparePassword(password);
  if (!isMatched) return next(new ErrorHandler("Invalid credentials", 400));

  const accessToken = jwt.sign({ id: user._id }, config.JWT_SECRET, {
    expiresIn: "45m",
  });

  const refreshToken = jwt.sign({ id: user._id }, config.JWT_SECRET);

  if (!user.tokens) user.tokens = [refreshToken];
  else user.tokens.push(refreshToken);

  await user.save();

  res.cookie("refreshToken", refreshToken, {
    maxAge: 15 * 24 * 60 * 60 * 1000,
    sameSite: "none",
    httpOnly: true,
    secure: true,
    partitioned: true,
  });
  res.cookie("accessToken", accessToken, {
    maxAge: 15 * 24 * 60 * 60 * 1000,
    sameSite: "none",
    httpOnly: true,
    secure: true,
    partitioned: true,
  });

  res.json({
    success: true,
    profile: {
      id: user._id,
      email: user.email,
      name: user.username,
      verified: user.verified,
      avatar: user.avatar?.url,
      accessToken: accessToken,
    },
    accessToken,
    refreshToken,
  });
});

Cors Config

app.use(
  cors({
    origin: [
      "https://mern-nextjs-ecommerce.vercel.app",
      config.ADMIN_CLIENT_URL,
      "http://localhost:3000",
    ],
    credentials: true,
    methods: ["GET", "POST", "PUT", "DELETE"],
    allowedHeaders: [
      "Content-Type",
      "Authorization",
      "Origin",
      "X-Requested-With",
      "Accept",
      "Set-Cookie",
      "Cookie",
    ],
  })
);

Frontend Submit Function

const handleSignInSubmit = async (data: SignInInput) => {
    try {
      const res = await fetch(`${process.env.NEXT_PUBLIC_API_URL}auth/signin`, {
        method: "POST",
        credentials: "include", // This ensures cookies are sent with the request
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          email: data.email,
          password: data.password,
        }),
      });

      const resData = await res.json();

       toast.success(resData.message || "Logged In !");
    } catch (error) {
      toast.error("An error occurred");
    }
  };