Puppeteer: Closing the browser when last page is closed sometimes throws an error

+1

Did a bit of quick debugging, the targetDestroyed event is fired before page.close() message has been acknowledged (or rather, puppeteer has processed the acknowledgement).

I can think of ways to fix it - eg wait for a Target.closeTarget acknowledgement before handling the targetDestroyed event. How to properly do that though is another question!

Thanks @MJPA for the investigation.

The issue comes from the fact that browser removes targets from the list before the associated pages are closed.

In the following example, I'd expect browser.pages() to report 1 page until the page.close() call is finished:

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const [page] = await browser.pages();
  browser.on('targetdestroyed', async () => console.log('Target destroyed. Pages count: ' + (await browser.pages()).length));
  console.log('closing page...');
  await page.close();
  console.log('page closed.');
  await browser.close();
})();

The output:

closing page...
Target destroyed. Pages count: 0
page closed.

@JoelEinbinder what do you think?

Same issue as @MJPA

        await page.waitForSelector('aside.aside a[href="/checkout"]')
    .then(() => {
        logMessage('Checkout is available');
    })
    .catch(err => {
        log('Checkout not available');
        success = false;
        browser.close();
    });
    // click checkout button
    await Promise.all([
        page.click('aside.aside a[href="/checkout"]'),
        page.waitForNavigation()
    ]);

In this case, always same errors occurred.

Maybe this puppeteer error.

I get the same error with a slightly similar implementation, but through listening to the close event on a page. The documentation isn't overly explicit on what "close" means, but according to it's implementation, close is fired _before_ the page is closed, so the following example doesn't work, similar to the targetdestroyed example.

const puppeteer = require('puppeteer');
const browser = await puppeteer.launch();

// create 5 test pages
for(let i=0; i<5; i++){

  let page = await browser.newPage();

  // listen to page close event and close browser
  // when all get closed
  page.on('close', async () => {
    let pages = await browser.pages();
    if(!pages.length){
      // will not get here!
      browser.close();
    }
  });

}

let pages = await browser.pages();

pages.forEach(async (page) => await page.close());  

I guess this _sort of_ makes sense, since the event is called close and not closed. I got around this on my own by emitting my own closed event in the close() promise callback and listening to that instead, which _does_ work.

page.close().then(() => {
  page.emit('closed');
});

The moral of the story seems to be there is no 100% guaranteed method of knowing when a browser is safe to close (without having to catch the exception). Please let me know if I'm missing something.

Possibly related to #3423?

I get this after closing all tabs in a browser and then attempting to open a new page

In the following example, I'd expect browser.pages() to report 1 page until the page.close() call is finished:

This would break the code in the above example. The last page closed, brower.pages().length would be 1, the browser would not be closed. Then no more target destroyed events would come and the browser would live forever.

I'd say this is user error, although it is subtle. Any calls to page.close should be awaited before calling browser.close().

If there are no user controlled pages, simply Promise.all all the page closes, then close the browser. There should be no need to listen to the targetdestroyed events. Or just call browser.close and let all the pages close by themselves.

If there are user controlled pages, then listen to the targetdestroyed events, but there should be no need to call page.close.

+1.
I started to see this error after closing popups with page.on("popup"). When a popup fires inside an Frame context sometimes I can't close it with "popup.close()" and the puppeteer leaves the tab opened, so when I try to close the entire browser, it throws an "Target Closed" error, and the script stop.

I use puppeteer 1.14, with Chrome 73 (I don't use Chromium)
The code that I use to close the browser

async close_browser() {
    for (let page of await this.browser.pages()) {
      await page.close({
        "runBeforeUnload": true
      });
    }
   await this.browser.close();
}