how to use user-data-dir but for multiple puppeteer windows

Question

So what I am trying to do is to open puppeteer window with my google profile, but what I want is to do it multiple times, what I mean is 2-4 windows but with the same profile - is that possible? I am getting this error when I do it:

(node:17460) UnhandledPromiseRejectionWarning: Error: Failed to launch the browser process!
[45844:13176:0410/181437.893:ERROR:cache_util_win.cc(20)] Unable to move the cache: Access is denied. (0x5)

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch({
    headless:false,
    '--user-data-dir=C:\\Users\\USER\\AppData\\Local\\Google\\Chrome\\User Data',
  );
  const page = await browser.newPage();
  await page.goto('https://example.com');
  await page.screenshot({ path: 'example.png' });
        
  await browser.close();
})();

Answer 1

Note: It is already pointed in the comments but there is a syntax error in the example. The launch should look like this:

const browser = await puppeteer.launch({
  headless: false,
  args: ['--user-data-dir=C:\\Users\\USER\\AppData\\Local\\Google\\Chrome\\User Data']
});

The error is coming from the fact that you are launching multiple browser instances at the very same time hence the profile directory will be locked and cannot be moved to reuse by puppeteer.

You should avoid starting chromium instances with the very same user data dir at the same time.

Possible solutions

• Make the opened windows sequential, can be useful if you have only a few. E.g.:

const firstFn = async () => await puppeteer.launch() ...
const secondFn = async () => await puppeteer.launch() ...

(async () => {
  await firstFn()
  await secondFn()
})();

• Creating copies of the user-data-dir as User Data1, User Data2 User Data3 etc. to avoid conflict while puppeteer copies them. This could be done on the fly with Node's fs module or even manually (if you don't need a lot of instances).
• Consider reusing Chromium instances (if your use case allows it), with browser.wsEndpoint and puppeteer.connect, this can be a solution if you would need to open thousands of pages with the same user data dir.
  Note: this one is the best for performance as only one browser will be launched, then you can open as many pages in a for..of or regular for loop as you want (using forEach by itself can cause side effects), E.g.:

const puppeteer = require('puppeteer')
const urlArray = ['https://example.com', 'https://google.com']

async function fn() {
  const browser = await puppeteer.launch({
    headless: false,
    args: ['--user-data-dir=C:\\Users\\USER\\AppData\\Local\\Google\\Chrome\\User Data']
  })
  const browserWSEndpoint = await browser.wsEndpoint()

  for (const url of urlArray) {
    try {
      const browser2 = await puppeteer.connect({ browserWSEndpoint })
      const page = await browser2.newPage()
      await page.goto(url) // it can be wrapped in a retry function to handle flakyness

      // doing cool things with the DOM
      await page.screenshot({ path: `${url.replace('https://', '')}.png` })
      await page.goto('about:blank') // because of you: https://github.com/puppeteer/puppeteer/issues/1490
      await page.close()
      await browser2.disconnect()
    } catch (e) {
      console.error(e)
    }
  }
  await browser.close()
}
fn()