I tried to create a default Windows profile with pre-configured app settings, including FF. I created a temporary user, logged in, installed FF and configured it, also installed some add-ons (first of all, ublock origin). Then I logged out, logged as an administrator and moved the temporary user profile to the default profile location (c:\Users\Temp -> c:\Users\Default), and then reset its NTFS permissions. This almost always works for all applications, including Google Chrome. I created a new user and logged in, opened FF. The settings were applied, but the extensions did NOT work, and even the buttons on the toolbar looked like empty squares. At the same time, the add-ons were present in the list of add-ons in settings, although without icons. It helped to turn off and turn on all the add-ons one by one, manually. After some research, I realized that FF binds its settings to absolute paths to add-on files (*.xpi), specifically in the $profile/extensions.json and $profile/addonStartup.json.lz4 files. Google Chrome, for example, doesn't do anything simular, like the vast majority of applications. Removing these files from the profile will cause all add-ons to be "reinstalled" on first launch and set to a disabled status. An easier way to reproduce the problem: 1. Run firefox -profile d:\temp\profile1 2. Install some extensions. 3. Rename profile1 folder to profile2. 4. Run firefox -profile d:\temp\profile2 5. Got it! For what purposes does firefox bind to absolute add-on paths, and how can this problem be solved? P.S. I know about portable firefox from PortableApps.com, but I don't want to use a third-party loader for my tasks.