Why is puppeteer reporting "UnhandledPromiseRejectionWarning: Error: Navigation failed because browser has disconnected!"?

Question

我有一个简单的 node.js 脚本来捕获一些网页的屏幕截图。看来我在使用 async/await 时被绊倒了，但我不知道在哪里。我目前正在使用 puppeteer v1.11.0.

const puppeteer = require('puppeteer');

//a list of sites to screenshot
const papers =
{
     nytimes: "https://www.nytimes.com/",
     wapo: "https://www.washingtonpost.com/"
};

//launch puppeteer, do everything in .then() handler
puppeteer.launch({devtools:false}).then(function(browser){

//create a load_page function that returns a promise which resolves when screenshot is taken
async function load_page(paper){

    const url = papers[paper];

    return new Promise(async function(resolve, reject){

        const page = await browser.newPage();
        await page.setViewport({width:1024, height: 768});

        //screenshot on first console message
        page.once("console", async console_msg => {        
            await page.pdf({path: paper + '.pdf',
                            printBackground:true,
                            width:'1024px',
                            height:'768px',
                            margin: {top:"0px", right:"0px", bottom:"0px", left:"0px"}
                        });

            //close page
            await page.close();

            //resolve promise
            resolve();
        });

        //go to page
        await page.goto(url, {"waitUntil":["load", "networkidle0"]});

    })     
}

//step through the list of papers, calling the above load_page()
async function stepThru(){
    for(var p in papers){
        if(papers.hasOwnProperty(p)){
            //wait to load page and screenshot before loading next page
            await load_page(p);
        }
    }

    //close browser after loop has finished (and all promises resolved)
    await browser.close();  
}

//kick it off
stepThru();

//getting this error message:
//UnhandledPromiseRejectionWarning: Error: Navigation failed because browser has disconnected!

});

Answer 1

Navigation failed because browser has disconnected 错误通常意味着启动 Puppeteer 的节点脚本没有等待 Puppeteer 操作完成就结束了。因此，正如您所说，这是一些等待的问题。

关于您的脚本，我做了一些修改以使其工作：

首先你不是在等待 stepThru 函数的（异步）结束所以改变

stepThru();

至

await stepThru();

和

puppeteer.launch({devtools:false}).then(function(browser){

至

puppeteer.launch({devtools:false}).then(async function(browser){

（我加了async）

我更改了您管理 goto 和 page.once 承诺的方式

PDF 承诺现在是：

new Promise(async function(resolve, reject){
    //screenshot on first console message
    page.once("console", async () => {
      await page.pdf({
        path: paper + '.pdf', 
        printBackground:true, 
        width:'1024px', 
        height:'768px', 
        margin: {
          top:"0px", 
          right:"0px", 
          bottom:"0px", 
          left:"0px"
        } 
      });
      resolve();
    });
})

它只有一个职责，就是创建 PDF。

然后我用 Promise.all

page.goto

await Promise.all([
    page.goto(url, {"waitUntil":["load", "networkidle2"]}),
    new Promise(async function(resolve, reject){
        // ... pdf creation as above        
    })
]);

我把 page.close 移到了 Promise.all

await Promise.all([
    // page.goto
    // PDF creation
]);

await page.close();
resolve();

现在它可以工作了，这里是完整的工作脚本：

const puppeteer = require('puppeteer');

//a list of sites to screenshot
const papers =
{
  nytimes: "https://www.nytimes.com/",
  wapo: "https://www.washingtonpost.com/"
};

//launch puppeteer, do everything in .then() handler
puppeteer.launch({devtools:false}).then(async function(browser){

  //create a load_page function that returns a promise which resolves when screenshot is taken
  async function load_page(paper){
    const url = papers[paper];
    return new Promise(async function(resolve, reject){
      const page = await browser.newPage();
      await page.setViewport({width:1024, height: 768});

      await Promise.all([
        page.goto(url, {"waitUntil":["load", "networkidle2"]}),
        new Promise(async function(resolve, reject){

          //screenshot on first console message
          page.once("console", async () => {
            await page.pdf({path: paper + '.pdf', printBackground:true, width:'1024px', height:'768px', margin: {top:"0px", right:"0px", bottom:"0px", left:"0px"} });
            resolve();
          });
        })
      ]);

      await page.close();
      resolve();
    })
  }

  //step through the list of papers, calling the above load_page()
  async function stepThru(){
    for(var p in papers){
      if(papers.hasOwnProperty(p)){
        //wait to load page and screenshot before loading next page
        await load_page(p);
      }
    }

    await browser.close();
  }

  await stepThru();
});

请注意：

我将 networkidle0 更改为 networkidle2 因为 nytimes.com 网站需要很长时间才能到达 0 网络请求状态（因为 AD 等).您可以等待 networkidle0 显然，但这取决于您，这超出了您的问题范围（在这种情况下增加 page.goto 超时）。
www.washingtonpost.com 站点出现 TOO_MANY_REDIRECTS 错误，因此我更改为 washingtonpost.com，但我认为您应该对此进行更多调查。为了测试脚本，我多次使用 nytimes 网站和其他网站。再说一次：这不在你的问题范围内。

如果您需要更多帮助，请告诉我

Answer 2

我在系统盘满的时候出现了同样的错误

Why is puppeteer reporting "UnhandledPromiseRejectionWarning: Error: Navigation failed because browser has disconnected!"?

Why is puppeteer reporting "UnhandledPromiseRejectionWarning: Error: Navigation failed because browser has disconnected!"?

node.js

google-chrome-headless

puppeteer