I'm running a UI deployment with a web-app and Firefox on an Ubuntu system. I'm running Firefox with the flag "--kiosk" to place it into kiosk mode (booted from the command line upon system boot). This works fine, and boots up Firefox to the page I want (my web-app) in kiosk mode (full-screen, etc.) However, I get very annoying popups that are not acceptable for deployments in front of customers. I have tried, but CANNOT suppress all of them, or, when I thought I did, they came back a month later. Popups: 1. "Keep pesky trackers off your tail. Open my links with Firefox" 2. "Welcome back" 3. Others like this... These are Firefox browser popups, not related to popups that other websites can put up, and block the entire screen with an overlay until they are dismissed. My deployments are only going to a single web-page that I control (which has no popups) and there is no keyboard on the deployed system, so people cannot navigate elsewhere. Things I've tried: 1. Firefox is installed via snap, which provides "snapshotting" configuration for the Firefox snap. I loaded Firefox, cleared the annoying dialogs, and then took a snapshot (theorying that I set Firefox configuration when doing this, and I capture that in the snapshot) and re-installed it onto a new system. Still go popups 2. Looked into user.js preferences. I can install this file onto the system, so I looked through https://searchfox.org/mozilla-release/source/remote/shared/RecommendedPreferences.sys.mjs and this is how I initially got all the popups to disable themselves. I looked through that list and tested most of the recommended settings until the popups disappeared. However, after a month or so, I'm beginning to see the popups again. Any suggestions from Mozilla or others that run into this issue?