directory/browser/defaults/profile/ strikes me as being in the wrong location, like in the Program Files = Firefox program /defaults/ folder rather than in the C:\Users\user\AppData\Roaming\Mozilla\Firefox\Profiles\profile-name folder.

The optional user.js file belongs in the Profile folder which is located under Roaming.

You can use Help > Troubleshooting Information within Firefox to get to the correct folder for the Profile being used -- at Profile Folder and then use the Open Folder button in the UI list in the left column.

HI,

Thanks for the reply.

Here, am launching firefox not on Windows but on linux based machine. So normally in firefox..whatever files we keep under installed_directory/browser/defaults/profile directory will copy it to the newly created profile directory for example /.user_homedirectory/.mozilla/firefox/randomname_directory/ . But it is not happening now..If i copy the user.js manually to /.user_homedirectory/.mozilla/firefox/randomname_directory/ everything is working fine. But i want to automate that for every user. So where I need to keep user.js in order to automatically copy it newly created profile or opened sessions

TIA

I'm not sure if this way of initializing a profile is still supported. Maybe try to place the file in "browser/defaults/preferences" instead. Otherwise you need to use a autoconfig.cfg file to copy the file(s) yourself to the profile folder.

It is probably better to use the autoconfig.cfg or policies.json file to initialize prefs.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig
• https://github.com/mozilla/policy-templates/blob/master/README.md