Resolving print dialog issues in headless Selenium C# automation

Other Questions Headless Browser
1

Hey folks, I’m stuck with a problem in my Selenium C# automation. I’m trying to handle the print dialog in a headless browser, but I’m running into some trouble.

Here’s a snippet of what I’ve tried:

var driver = new ChromeDriver();
driver.Url = "https://example.com";

((IJavaScriptExecutor)driver).ExecuteScript("window.print();");

var printButton = driver.FindElement(By.CssSelector("#print-button"));
printButton.Click();

// Attempt to close print dialog
var closeButton = driver.FindElement(By.Id("close-dialog"));
closeButton.Click();

But when I run this in headless mode, I get an error saying it can’t find the elements. Any ideas on how to properly handle the print dialog in a headless browser? I’ve heard something about using shadow DOM, but I’m not sure how to implement it. Any help would be appreciated!

2

I’ve dealt with similar headaches in my automation projects. One workaround that’s been a game-changer for me is using Chrome’s DevTools Protocol. It gives you way more control over the browser, especially in headless mode.

Here’s a rough idea of how you could approach it:

var options = new ChromeOptions();
options.AddArgument("--headless");

var driver = new ChromeDriver(options);
var devTools = driver.GetDevToolsSession();

await devTools.SendAsync(Page.SetDownloadBehavior(DownloadBehavior.Allow, "/path/to/save/"));

driver.Navigate().GoToUrl("https://example.com");

await devTools.SendAsync(Page.PrintToPDF());

This method bypasses the print dialog entirely and gives you a PDF directly. It’s been pretty reliable in my experience, even with complex pages. Just remember to tweak the PDF settings to match your needs. Good luck with your project!

3

I’ve encountered this issue in my automation projects as well. One effective approach I’ve found is to use Chrome’s built-in PDF printing capabilities instead of trying to interact with the print dialog directly. You can achieve this by setting specific Chrome options:

var options = new ChromeOptions();
options.AddArgument("--headless");
options.AddArgument("--disable-gpu");
options.AddArgument("--print-to-pdf=/path/to/output.pdf");

var driver = new ChromeDriver(options);
driver.Navigate().GoToUrl("https://example.com");

This method bypasses the need to handle the print dialog altogether and directly saves the page as a PDF. It’s been quite reliable in my experience with headless automation.

4

hey scarlettturner, i’ve hit similar issues before. for headless, you might wanna try using chrome options to set up a custom print settings. something like:

var options = new ChromeOptions();
options.AddArgument(“–kiosk-printing”);

this bypasses the dialog altogether. hope it helps!