How to log the response of a failed requests in K6

Hello Team, Could someone please tell me how can i log the responses of failed requests to a file??

I can view them by executing console.log or by running --http-debug=full test.js > http_debug.txt. However, http_debug.txt records both successful and unsuccessful measurements and I dont want to log it in consoleIn the future, there will be millions of transactions, which I believe will be unfeasible to add to http_debug.txt or in console.

I tried checks and counters, but they only give me the amount of unsuccessful requests, not the response bodyof those requests. Is there a way to accomplish this?

I tried the suggestions in the forum, but nothing seems to work.

Thank you.

Hi @bjrakshita !

You can try to achieve this with xk6-file extension.

import http from "k6/http";
import file from 'k6/x/file';

const urls=["", "", "", ""];

function randomUrl(){
    return urls[Math.floor(Math.random() * urls.length)];

function headersToString(headers){
    let ret =""
    for (var key in headers){
        ret += key + ": " + headers[key]+"\n";
    return ret;

function responseToString(r){
    let ret = "Request:\n"
    ret += r.request.method+" "+r.request.url+"\n"
    ret += headersToString(r.request.headers)+"\n";
    ret += r.request.body+"\n";
    ret += "Response:\n"
    ret += r.status_text+"\n"   
    ret += headersToString(r.headers)+"\n";
    ret += r.body+"\n";
    return ret;

export default function () {
  let url= randomUrl();
  let r = http.get(url);

  if (r.status != 200){  // if status is not 200 write request+response to file
    file.appendString("output.txt", responseToString(r)+'\n');

You can run it with a custom k6 binary after building it with xk6

xk6 build --with

Or you can run it simply with after installing it.

k6x run script.js