Koa+mongo reports error: Error: connect ECONNREFUSED 127.0.0.1 after receiving post request

problem description

after the post request is sent by the current end, the database successfully writes the data, but the backend still reports an error of Error: connect ECONNREFUSED 127.0.0.1, and returns 500.

the environmental background of the problems and what methods you have tried

the backend is built with koa, and mongoose operates the database. I checked that the default returned port is 80, but 80 is inaccessible, so I added a proxy

to the app.js of koa.

var proxy = require("koa-better-http-proxy")

app.use(
  proxy("/register", { target: "http://127.0.0.1:3000", changeOrigin: true })
)

related codes

//User.js
router.post("/register", async ctx => {
  const { username, password, email } = ctx.request.body
  let user = User.find({
    username
  })
  if (user.length) {
    ctx.body = {
      code: -1,
      msg: ""
    }
  }

  let newUser = await User.create({
    username,
    password,
    email
  })
  if (newUser) {
    let res = await axios.post("/login", {
      username,
      password
    })

    if (res.data && res.data.code === 0) {
      ctx.body = {
        code: 0,
        msg: "",
        user: res.data.user
      }
    } else {
      ctx.body = {
        code: -1,
        msg: "error"
      }
    }
  } else {
    ctx.body = {
      code: -1,
      mgs: ""
    }
  }
})

router.post('/login', async (ctx, next) => { // ctx.body = { // code: 0, // msg: { // ...ctx.request.body // } // } return passport.authenticate('local', function(err, user, info, status) { if (err) { ctx.body = { code: -1, msg: err } } else { // if (user) { ctx.body = { code: 0, msg: '', user } return ctx.login(user) } else { ctx.body = { code: 1, msg: info } } } })(ctx, next)