Express only sends response on the first request

I have this backend API i am working on, i’m trying to implement alternative telegram authentication beside the official Telegram widget or passport auth. so i have a POST request which wait for 30min until it get the message from user on telegram through telegram bot. the issue is when i send the FIRST request and also send back “/start (code)” on the bot it works as i expected but it doesn’t work for more than one time. it console log error: [polling_error] {"code":"ERR_HTTP_HEADERS_SENT"}, i’m sending back only one response on request. i don’t understand where this error is coming from. i’m using “node-telegram-bot-api” to interact with telegram bot API.

here’s what my code looks like:


exports.signIn = (req, res, next) => {
    const { botSignInHandler } = require("./handlers");
    const { signInMethod } = req.params;

    if (signInMethod === "bot") {
        req.setTimeout(1800000); // 30 min

        let { startId } = req.query;

        if (startId) {
            return botSignInHandler(startId, bot, (user) => {
                bot.sendMessage(user.chat_id, "success");
        } else {
            let err = new Error("start-id not found");
            err.statusCode = 400;
            return next(err);


exports.botSignInHandler = (startId, bot, cb) => {
    return bot.on("message", (msg) => {
        let user = {
            last_name: ? : "",
            avatar: uiAvatar(,

        let text = msg.text;
        let _id = text.split(" ")[1];

        if (_id === startId) return cb(user);

That error means you already sent a response but you’re trying to send another one for the same request. Put a console.log as the first line in botSignInHandler and see if it’s being called twice.

Also, does bot.sendMessage end the request/response cycle? Maybe that counts as response #1, I don’t know I’m not familiar with that API.