问无法获得响应，显示`users.findOne()操作在10000 to后超时

EN

`users.findOne()` buffering timed out after 10000ms

import React, { useState } from "react";
import { useHistory } from "react-router-dom";
import imgpath from "../assets/notepic.jpg";
import { motion } from "framer-motion";

const Login = (props) => {
  let history = useHistory();
  let port = process.env.PORT;
  ....
 
  const handleSubmit = async (e) => {
    e.preventDefault();
    const response = await fetch(`https://my-notebook-mohit.herokuapp.com:/api/auth/login`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({
        email: credentials.email,
        password: credentials.password,
      }),
    });
    const json = await response.json();
    if (json.success === true) {
      //storing the authtoken
      localStorage.setItem("token", json.authToken);
      props.showAlert("User logged in successfully", "info");
      history.push("/");
    } else {
      props.showAlert("invalid Credentials", "danger");
    }
    console.log(json);
  };

  return (
   .....
   <form onSubmit={handleSubmit} className="login-form">
           .....
           ....
   </form>
  ...
  ...

};

export default Login;

const express = require("express");
const { body, validationResult } = require("express-validator");
const router = express.Router();
const User = require("../models/User");
const bcrypt = require("bcryptjs");
const jwt = require("jsonwebtoken");
const JWT_SECRET = "mohitisagood$boy";
const fecthUser = require("../middleware/fetchUser");

//ROUTE 1 :Creating a User :POST - "/api/auth/createuser"
router.post(
  "/createuser",
  [
    body("name", "Name must have at least 3 characters").isLength({ min: 3 }),
    body("email", "Enter a valid email").isEmail(),
  ],
  async (req, res) => {

    let success = false;
    //If there are errors, then return bad request + Errors
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({success, errors: errors.array() });
    }

    try {
      //Check whether email exists
      let user = await User.findOne({ email: req.body.email });
      //console.log("user.nemail = " + user);
      if (user) {
        //console.log(user.email);
        return res.status(400).json({success, error: "Email Already Taken" });
      }

      //hashing the password here
      const salt = await bcrypt.genSalt(10);
      const secPass = await bcrypt.hash(req.body.password, salt);
      //user is created
      user = await User.create({
        name: req.body.name,
        email: req.body.email,
        password: secPass,
      });

      //passing the id as data to make jwt token
      const data = {
        user: {
          id: user.id,
        },
      };

      const authToken = jwt.sign(data, JWT_SECRET);
      //console.log(authToken)

      
      success = true;
      //res.json(user);
      res.json({success, authToken });
    } catch (error) {
      console.log(error.message);
      res.status(500).send("internal server error");
    }
  }
);

//ROUTE 2 :Authenticating a User :POST - "/api/auth/login"
router.post(
  "/login",

  body("email", "Enter a valid email").isEmail(),

  async (req, res) => {
    //If there are errors, then return bad request + Errors
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({ errors: errors.array() });
    }

    const { email, password } = req.body;
    
    let success = false;

    try {
      let user = await User.findOne({ email });

      // console.log("user - "+user)

      if (!user) {
        res.status(400).json({success,error:"Login with correct credentials!"});
      }

      //compare the pwd bw 'hash of pwd entered' & 'hash from your pwdDB'
      const passwordCompare = await bcrypt.compare(password, user.password);

      if (!passwordCompare) {
        res.status(400).json({success,error:"Login with correct credentials!"});
      }
      //nodemon crashes whenever PASSWORD === NULL


      const payload = {
        user: {
          id: user.id,
        },
      };

      const authToken = jwt.sign(payload, JWT_SECRET);
      
      success = true;
      res.json({ success, authToken });
    } catch (error) {
      console.log(error.message);
      res.status(500).send("Internal Server Error");
    }
  }
);

//ROUTE 3 :Get Loggedin user details  :GET - "/api/auth/getUser" LOGIN REQUIRED;

router.get("/getUser", fecthUser, async (req, res) => {
  try {
    const userid = req.user.id; //gets userid from fetchUser middleware fn
    let user = await User.findById(userid);
    res.send(user);
  } catch (error) {
    console.log(error.message);
    res.status(500).send("Internal Server Error");
  }
});

module.exports = router;

const mongoose = require("mongoose");
const { Schema } = mongoose;

const UserSchema = new Schema({
  name: {
    type: String,
    required: true,
  },
  email: {
    type: String,
    required: true,
  },
  password: {
    type: String,
    required: true,
    validate(value) {
      if(value.length < 5) {
        throw new Error( "Minimum length is 5 characters");
      }
      else if (!value.match(/\d/) || !value.match(/[a-zA-Z]/) ) {
        throw new Error(
          "Password must contain at least one letter and one number"
        );
      }

    }
    
  },
  date: {
    type: Date,
    default: Date.now,
  },
});

const User = mongoose.model("users", UserSchema);
module.exports = User;

2022-01-19T13:53:34.121500+00:00 heroku[web.1]: Starting process with command `npm start`
2022-01-19T13:53:35.255548+00:00 app[web.1]: 
2022-01-19T13:53:35.255561+00:00 app[web.1]: > my-notebook-backend@1.0.0 start
2022-01-19T13:53:35.255561+00:00 app[web.1]: > node index.js
2022-01-19T13:53:35.255562+00:00 app[web.1]: 
2022-01-19T13:53:35.891508+00:00 heroku[web.1]: State changed from starting to up
2022-01-19T13:53:36.331033+00:00 heroku[router]: at=info method=GET path="/" host=my-notebook-mohit.herokuapp.com request_id=1f84a49c-8785-4483-a148-1ee8e2d02733 fwd="116.179.32.83" dyno=web.1 connect=0ms service=6ms status=404 bytes=415 protocol=http
2022-01-19T13:53:35.670089+00:00 app[web.1]: my-notebook backend listening at http://localhost:28800
2022-01-19T13:54:05.041186+00:00 heroku[router]: at=info method=OPTIONS path="/api/auth/login" host=my-notebook-mohit.herokuapp.com request_id=ce943a7c-d99d-41a9-965f-7d9f420c0abc fwd="157.34.168.68" dyno=web.1 connect=0ms service=3ms status=204 bytes=301 protocol=https
2022-01-19T13:54:05.563326+00:00 app[web.1]: Connected to Mongo Successfully!
2022-01-19T13:54:15.670120+00:00 heroku[router]: at=info method=POST path="/api/auth/login" host=my-notebook-mohit.herokuapp.com request_id=9527d47f-e054-4f83-bb95-7e99582dab31 fwd="157.34.168.68" dyno=web.1 connect=0ms service=10030ms status=500 bytes=272 protocol=https
2022-01-19T13:54:15.666381+00:00 app[web.1]: Operation `users.findOne()` buffering timed out after 10000ms
2022-01-19T13:54:17.866396+00:00 app[web.1]: Operation `users.findOne()` buffering timed out after 10000ms
2022-01-19T13:54:17.868120+00:00 heroku[router]: at=info method=POST path="/api/auth/login" host=my-notebook-mohit.herokuapp.com request_id=4e9561f7-1050-4afb-9f6b-bf04c876b858 fwd="157.34.168.68" dyno=web.1 connect=0ms service=10007ms status=500 bytes=272 protocol=https