Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window.

[MagdelineNg]

System

• Version: 0.34.0 (Installed with GeckoDriverManager
• Platform: Win11
• Firefox: 125.0.3
• Selenium: 3.141.0

Testcase

import configparser
import os

web_driver = selenium_webdriver.Firefox(executable_path='C:\\Users\\mnxl\\.wdm\\drivers\\geckodriver\\win64\\v0.34.0\\geckodriver')
profile = web_driver.capabilities['moz:profile']

Path to the Firefox profiles folder
profiles_path = os.path.expanduser(r'~\AppData\Roaming\Mozilla\Firefox')

Path to the profiles.ini file
profiles_ini_path = os.path.join(profiles_path, 'profiles.ini')

Read the profiles.ini file
config = configparser.ConfigParser()
config.read(profiles_ini_path)

Find the section for the profile to set as default
for section in config.sections():

   if config.has_option(section, 'Path') and config.get(section, 'Path') == profile:
       # Set this profile as the default
       config.set(section, 'Default', '1')
   else:
       # Set all other profiles as not default
       config.set(section, 'Default', '0')
Write the changes back to the profiles.ini file
with open(profiles_ini_path, 'w') as configfile:

   config.write(configfile)

Stacktrace

1714986617679 geckodriver INFO Listening on 127.0.0.1:64390
1714986620687 mozrunner::runner INFO Running command: "C:\Program Files\Mozilla Firefox\firefox.exe" "--marionette" "-profile" "C:\Users\ngm1admin\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default" "-no-remote"
Read port: 55353
console.warn: services.settings: Ignoring preference override of remote settings server
console.warn: services.settings: Allow by setting MOZ_REMOTE_SETTINGS_DEVTOOLS=1 in the environment
1714986621150 Marionette INFO Marionette enabled
1714986621195 Marionette INFO Listening on port 64403
Read port: 64403
1714986622852 RemoteAgent WARN TLS certificate errors will be ignored for this session
JavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 759: WebGL context was lost.
JavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 726: WebGL warning: : AllowWebgl2:false restricts context creation on this system.
JavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 726: Failed to create WebGL context: WebGL creation failed:

• AllowWebgl2:false restricts context creation on this system. ()
  JavaScript error: resource://gre/modules/PromiseWorker.sys.mjs, line 75: Error: Could not get children of `C:\Users\ngm1admin\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default\thumbnails': directory does not exist (NS_ERROR_FILE_NOT_FOUNJavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 759: WebGL context was lost.
  JavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 726: WebGL warning: : AllowWebgl2:false restricts context creation on this system.
  JavaScript warning: resource://gre/modules/Troubleshoot.sys.mjs, line 726: Failed to create WebGL context: WebGL creation failed:
• AllowWebgl2:false restricts context creation on this system. ()
  1714986833087 Marionette INFO Stopped listening on port 64403
  JavaScript error: chrome://remote/content/marionette/cert.sys.mjs, line 47: NS_ERROR_NOT_AVAILABLE: Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsICertOverrideService.setDisableAllSecurityChecksAndLetAttackersInterceptMyData]
  1714988730424 geckodriver INFO Listening on 127.0.0.1:64722
  1714988733431 geckodriver::browser DEBUG Backing up prefs to "C:\Users\ngm1admin\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default\user.geckodriver_backup_2"
  1714988733446 mozrunner::runner INFO Running command: "C:\Program Files\Mozilla Firefox\firefox.exe" "--marionette" "-profile" "C:\Users\ngm1admin\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default" "-no-remote"
  1714988733631 geckodriver::marionette DEBUG Waiting 60s to connect to browser on 127.0.0.1
  Read port: 64477
  console.warn: services.settings: Ignoring preference override of remote settings server
  console.warn: services.settings: Allow by setting MOZ_REMOTE_SETTINGS_DEVTOOLS=1 in the environment
  1714988733994 Marionette INFO Marionette enabled
  1714988733995 RemoteAgent DEBUG Setting recommended pref browser.tabs.warnOnClose to false
  1714988733995 RemoteAgent DEBUG Setting recommended pref datareporting.policy.dataSubmissionPolicyAccepted to false
  1714988733995 RemoteAgent DEBUG Setting recommended pref dom.max_chrome_script_run_time to 0
  1714988733995 RemoteAgent DEBUG Setting recommended pref network.http.prompt-temp-redirect to false
  1714988733995 RemoteAgent DEBUG Setting recommended pref privacy.trackingprotection.enabled to false
  1714988733997 Marionette TRACE Received observer notification final-ui-startup
  1714988734011 Marionette INFO Listening on port 64735
  1714988734011 Marionette DEBUG Marionette is listening
  1714988734618 Marionette TRACE Received observer notification browser-idle-startup-tasks-finished
  1714988735666 geckodriver::marionette TRACE Retrying in 100ms
  Read port: 64735
  1714988735773 Marionette DEBUG Accepted connection 0 from 127.0.0.1:64741
  1714988735774 geckodriver::marionette DEBUG Connection to Marionette established on 127.0.0.1:64735.
  1714988735779 Marionette DEBUG 0 -> [0,1,"WebDriver:NewSession",{"acceptInsecureCerts":true,"browserName":"firefox"}]
  1714988735781 RemoteAgent WARN TLS certificate errors will be ignored for this session
  1714988735781 Marionette DEBUG Waiting for initial application window
  1714988735784 RemoteAgent TRACE [3] ProgressListener Start: expectNavigation=false resolveWhenStarted=false unloadTimeout=5000 waitForExplicitStart=false
  1714988735784 RemoteAgent TRACE [3] ProgressListener Setting unload timer (5000ms)
  1714988735784 RemoteAgent TRACE [3] Document already finished loading: about:blank
  1714988735784 RemoteAgent TRACE [3] ProgressListener Stop: has error=false
  1714988735789 Marionette DEBUG 0 <- [1,1,null,{"sessionId":"8d6e0192-7663-42a1-b9ac-8a331231523e","capabilities":{"browserName":"firefox","browserVersion":"125.0.3","platformName":"windows","acceptInsecureCerts":true,"pageLoadStrategy":"normal","setWindowRect":true,"timeouts":{"implicit":0,"pageLoad":300000,"script":30000},"strictFileInteractability":false,"unhandledPromptBehavior":"dismiss and notify","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:125.0) Gecko/20100101 Firefox/125.0","moz:accessibilityChecks":false,"moz:buildID":"20240425211020","moz:headless":false,"moz:platformVersion":"10.0","moz:processID":12992,"moz:profile":"C:\Users\ngm1admin\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default","moz:shutdownTimeout":60000,"moz:webdriverClick":true,"moz:windowless":false,"proxy":{}}}]
  1714988735793 webdriver::server DEBUG <- 200 OK {"value":{"sessionId":"8d6e0192-7663-42a1-b9ac-8a331231523e","capabilities":{"acceptInsecureCerts":true,"browserNam ... avior":"dismiss and notify","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:125.0) Gecko/20100101 Firefox/125.0"}}}

Receiving this error:
Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window.

My desktop app redirects user to a login screen on Firefox, and I want to automate it using Selenium. My current workflow:

1. Launch Selenium-controlled Firefox browser using GeckoDriver
2. Click on "Login" button on my desktop app. The desktop app launches the login screen on user's OS default browser using the default user profile (in which case I set in profiles.ini to the temp profile copy created by Selenium).
3. (ERROR) Popup on the above error is displayed

[whimboo]

Could you please attach a trace-level log from geckodriver? Read more about reporting actionable bugs in our contribution guidelines.

[MagdelineNg]

I have updated the stracktrace @whimboo . I am also receiving this

[whimboo]

The first launch of Firefox somehow failed and maybe these WebGL warnings indicate a problem. After that Firefox gets started a second time and not Marionette runs successfully. I'm not sure why its failing first and why it's started a 2nd time. The code above doesn't indicate that. Also the profile manager dialog should never be seen given that geckodriver doesn't make use of the -P argument of Firefox. So something else might come into play here.

[MagdelineNg]

@whimboo I am adding the new user profile selenium creates into profiles.ini, and I launch my desktop app manually after running the code above. Reason for updating profiles.ini is that my desktop app follows the user's default browser settings and user profile to redirect user to the login url screen. However, I receive the "Firefox - Choose User Profile" upon launching my app

[whimboo]

If you are launching Firefox manually with more than a profile available then you will indeed get the profile manager shown. There you will have to select the newly created / added profile. Is this window empty? If yes, then check the updated profiles.ini if entries are correctly set. Otherwise the UI might not list any profiles.

Further you most likely need the -remote argument when launching Firefox, or you have to set the MOZ_NO_REMOTE=1` environment variable to indicate Firefox to not re-use an already open Firefox instance.

[MagdelineNg]

@whimboo Should I be removing the -no-remote and -new-instance arguments, as they seem to be added by default by FirefoxOptions(). I want to ensure my new login url screen opens in the existing Firefox instance, does that mean "reusing the same Firefox instance" for my use case?

I understand Selenium creates a user profile (for example, C:\Users\mnxl\AppData\Local\Temp\rust_mozprofileXXbpxK), which I get from my code in web_driver.capabilities['moz:profile'] and set it as default in profiles.ini , so that my desktop app can launch the login url in the Selenium-controlled browser.

Here is my profiles.ini (I make sure to delete Profile1 after running the code above every time so there are no duplicate profiles):

[Install308046B0AF4A39CB]
default = 0
locked = 1
Default=Profiles/982casda.Default
Locked=1

[Profile1]
name = NewProfile
isrelative = 1
path = C:\Users\mnxl\AppData\Roaming\Mozilla\Firefox\Profiles\4qeq4qz4.Default
default = 1

[Profile0]
Name=Default
IsRelative=1
Path=Profiles/982casda.Default

[General]
startwithlastprofile = 0
version = 2
default = 0
Version=2

[BackgroundTasksProfiles]
mozillabackgroundtask-308046b0af4a39cb-defaultagent = 9jdb6ygt.MozillaBackgroundTask-308046B0AF4A39CB-defaultagent
mozillabackgroundtask-308046b0af4a39cb-backgroundupdate = 4n7ck25n.MozillaBackgroundTask-308046B0AF4A39CB-backgroundupdate
default = 0

Is this a possible approach to ensure my login url is launched in the existing firefox instance that I start with selenium webdriver?

Update: I removed -no-remote manually from the command and ran it to launch the Firefox browser like so "C:\\Program Files\\Mozilla Firefox\\firefox.exe" "--marionette" "-profile" C:\Users\NGM1AD~1\AppData\Local\Temp\rust_mozprofileRGuu0Q and my app was able to detect it. My question is, is it possible to remove the -no-remote from the code below?

binary = FirefoxBinary(r"C:\Program Files\Mozilla Firefox\firefox.exe")
browser_options = FirefoxOptions()
browser_options.log.level = "trace"
os.environ['MOZ_NO_REMOTE'] = '0'   #does not work

web_driver = selenium_webdriver.Firefox(options=browser_options, firefox_binary=binary, executable_path=GeckoDriverManager().install())

Here is the browser options (that I believe is set by selenium webdriver by default) since it's not in the code:

[whimboo]

It's still not clear to me how the order of steps are. You said that you are using the script and geckodriver to create a Firefox profile that you are using manually afterward. But now it's about connecting to an existing Firefox instance. Note that you cannot replace the underying profile while Firefox is running. Also I do not know how well Selenium actually supports this use case. Usually automation or tests create their own Firefox instance.

[whimboo]

No further feedback from reporter. As such I'm going to close this issue.