I was trying to run headless firefox with custom firefox profile over a selenium grid, But the browser does not open is headless mode. It opens in the GUI mode

Launch Firefox Grid
Set Download Directory
${profile path}= set_firefox_profile ${DOWNLOAD_DIR}
log ${profile path}
${dict} Create Dictionary seleniumProtocol=WebDriver maxInstances=5 environment=firefox
Open Browser about:blank headlessfirefox None http://192.168.99.100:4444/wd/hub desired_capabilities=${dict} ff_profile_dir=${profile path}
Maximize Browser Window

The firefox profile was created like this:
def set_firefox_profile(download_dir): fp = FirefoxProfile() fp.set_preference("browser.download.folderList", 2) fp.set_preference("browser.download.manager.showWhenStarting", False) fp.set_preference("browser.download.dir", download_dir) fp.set_preference("browser.manager.closeWhenDone", True) fp.set_preference("browser.download.manager.showAlertOnComplete", False) fp.set_preference("browser.helperApps.neverAsk.saveToDisk", "text/plan") fp.update_preferences() return fp.path

I have 3.11.0 version of selenium and 3.1.1 version of SeleniumLibrary in my environment