Selenium working with Chrome, but not headless Chrome

I've developed a couple of Python scripts using Selenium and, at first, PhantomJS. While heading toward automated downloads, I switched for (headed) Firefox (which worked) and then Chrome with the headless option so I won't have the browser opening in front of me.

My first script, which accesses a page and a couple of HTML elements, works perfectly with headless Chrome.

The second one, however, works only with headed Chrome. If I add the "headless" option, it doesn't work anymore. When I try to print the HTML in headless mode to see why it cannot find the HTML element I'm looking for, all I have is :

<html xmlns="http://www.w3.org/1999/xhtml"><head></head><body></body></html>

With the headed Chrome, I have a complete HTML printed. This is how I start my headless Chrome :

options = webdriver.ChromeOptions()
options.add_argument("--ignore-certificate-errors") 
options.add_argument("headless") 
driver = webdriver.Chrome(chrome_options=options)

Again, note that this works in another of my script. The only difference here is that I need to log in to access the page, but even then, why would it work with the head? My script is made to log in automatically anyway by filling the form.

Python : 3.6.1, Chrome : 60.0.3112.78 (64 bits), Selenium : 3.4.3

Any idea? Thanks.

** EDIT: Here is the beginning of the code**

url = 'https://10.11.227.21/tmui/'
driver.get(url + "login.jsp")

html_source = driver.page_source
print(html_source)

blocStatus = WebDriverWait(driver, TIMEOUT).until(EC.presence_of_element_located((By.ID, "username")))
inputElement = driver.find_element_by_id("username")
inputElement.send_keys('actualLogin')
inputElement = driver.find_element_by_id("passwd")
inputElement.send_keys('actualPassword')
inputElement.submit()

Solution

I had a same experience like you, and solved it by using xvfb and pyvirtualdisplay.

I use chromedrive=v2.3.1, chrome-browser=v60 and Selenium=3.4.3

In Headless chrome, some of script seems not to work as expected.

Please refer to vpassapera's comment in https://gist.github.com/addyosmani/5336747.

How about try it like below,

from pyvirtualdisplay import Display

display = Display(visible=0, size=(800, 600))
display.start()

# Do Not use headless chrome option
# options.add_argument('headless')

url = 'https://10.11.227.21/tmui/'
driver.get(url + "login.jsp")

html_source = driver.page_source
print(html_source)

blocStatus = WebDriverWait(driver,    TIMEOUT).until(EC.presence_of_element_located((By.ID, "username")))
inputElement = driver.find_element_by_id("username")
inputElement.send_keys('actualLogin')
inputElement = driver.find_element_by_id("passwd")
inputElement.send_keys('actualPassword')
inputElement.submit()

display.stop()

xvfb is required to use "pyvirtualdisplay"

$ sudo apt-get install -y xvfb