Chrome download error when downloading file with Puppeteer

Question

I have an application that shows a page, the user clicks on a button, and downloads a CSV file. I want to run this with Puppeteer.

Problem is that the CSV is downloaded empty and with an error. This happens both with headless true and false. The page finished loading, and I increased the timeout, but it still fails. What could be the issue?

const puppeteer = require('puppeteer');

(async () => {
    
    const browser = await puppeteer.launch({
       headless: false
    });

    const page = await browser.newPage();
    await page.goto('http://localhost:4400/login', { waitUntil: 'networkidle2' });    
    
    await page._client.send('Page.setDownloadBehavior', {
        behavior: 'allow',
        downloadPath: './',
    });

    await page.waitForSelector('#run-and-export');
    await page.click('#run-and-export');
  
    // file-downloaded is turned on when the file finished downloading (not to close the window)
    await page.waitForSelector('#file-downloaded', { timeout: 120000 }); 

    await browser.close();
    
})();

The code in the application that generates the file to download is an Angular service:

@Injectable({ 
    providedIn: 'root' 
})
export class DownloadService {

    downloadFile(content:any, fileName: string, mimeType: string){
    
        var blob = new Blob([(content)], {type: mimeType});
        var a = document.createElement('a');
        a.href = window.URL.createObjectURL(blob);
        a.download = fileName;
        a.click();

    }
}

Answer 1

This is what made this work:

const downloadPath = path.resolve('/my/path');

await page._client.send('Page.setDownloadBehavior', {
    behavior: 'allow',
    downloadPath: downloadPath 
});