If Firefox (on Windows) is updated by running the installer (as might be done in a deployment environment) rather than internally, it handles the two methods of including add-ons intended for all users differently. The two types are: (1) Add-on in ..\browser\extensions: all user profiles get the add-on (disabled by default) and can only enable/disable, not remove. (2) Add-on in ..\distribution\extensions: all *new user profiles* get the (enabled) add-on as a default that they can remove (and not have return) if they choose. (Sidenote: It would be nice if there were another, compromise choice that pushes an extension to all users but allows them to remove it.) Both kinds of add-ons are untouched if the internal updater for Firefox does its job. However: Add-ons placed (deployed) as (1) will remain if Firefox is updated by downloading and running an installer. Add-ons placed (deployed) as (2) are deleted if Firefox is updated this same way. This is really annoying when trying to push add-ons as defaults for new users. Is this a "feature"? I can't imagine why it would be, but I'm not a developer. If not, how can it be filed as a bug? Thanks.