Hi Shawn,

First thanks so much for writing this. I need headless download pretty bad so was excited to see you had something going. I have a JS heavy front end i need to be able to download in headless mode. Quite simply I can get your code running just fine, but it doesn't download. If I flip the headless flag my downloads happen. My assert fails after wait_for_file_to_exist times out. I wish I could share the page but it is private. Any idea on how to start debugging this would be helpful. I'm using:

Chrome Version 63.0.3239.108 (Official Build) (64-bit)
ChromeDriver 2.34.522932
python selenium (3.8.0)

the failing code is the assert after:

wait_until_file_exists(actual_file, 10)
assert (os.path.isfile(actual_file))

i am getting this response after enable_download_in_headless_chrome():

response from browser:
result:sessionId:1c43c8fa88866870389be5896efe77ed
result:status:0
result:value:None

Update After more investigation it appears that I can successfully run your code with my config so it must be something with the page I'm trying to interact with in headless mode. I'm investigating further and post my findings here in case someone else runs into the issue.

Update 2 I've found that the page should open a new chrome tab when clicking download, download the file and then close the tab. After clicking download the new tab doesn't open in headless mode. So I'm investigating tabs now.