Selenium returning error only in headless mode C#

Question

So far all my tests are running ok, to improve speed I was trying to run all in headless mode, but a bunch of those tests are failing, one of those had the following error:

  OpenQA.Selenium.ElementNotInteractableException: element not interactable
      (Session info: headless chrome=87.0.4280.141)
  Rastreamento de Pilha: 
    RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse)
    RemoteWebDriver.Execute(String driverCommandToExecute, Dictionary'2 parameters)
    RemoteWebElement.Execute(String commandToExecute, Dictionary'2 parameters)
    RemoteWebElement.Click()

The line that returned that error is

Driver.FindElement(By.CssSelector("#page_content_inner > div.uk-grid > div > div:nth-child(2) > div > div > div > ul > li:nth-child(2) > a")).Click();

Other ones had click intercepted:

      (Session info: headless chrome=87.0.4280.141)
  Rastreamento de Pilha: 
    RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse)
    RemoteWebDriver.Execute(String driverCommandToExecute, Dictionary'2 parameters)
    RemoteWebElement.Execute(String commandToExecute, Dictionary'2 parameters)
    RemoteWebElement.Click()

The line that generated the error is:

Driver.FindElement(By.Id("ClientesConvenio")).Click();

My true question is: Is there any limitations to headless mode? is there any beginners knowledge that I should have to use headless mode? why is this happening?

Answer 1

As @Nick Bailey mentioned in his comments at times ...headless mode behaves differently from the full browser... due to:

• Default Viewport
• element's in-view center point

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Solution

Ideally to Click() on the element you have to induce WebDriverWait for the ElementToBeClickable() and you can use either of the following Locator Strategies :

• Id :

   new WebDriverWait(driver, TimeSpan.FromSeconds(10)).Until(ExpectedConditions.ElementToBeClickable(By.Id("ClientesConvenio"))).Click();

• CssSelector :

   new WebDriverWait(driver, TimeSpan.FromSeconds(20)).Until(ExpectedConditions.ElementToBeClickable(By.CssSelector("#page_content_inner > div.uk-grid > div > div:nth-child(2) > div > div > div > ul > li:nth-child(2) > a"))).Click();

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References

You can find a couple of relevant detailed discussion in:

• Not able to maximize Chrome Window in headless mode