Although Mozilla has a [https://ftp.mozilla.org/pub/mobile/releases/40.0/android-x86/en-US/ website] with old versions of Firefox for testing purposes, it is not recommended that you use anything but the latest version. * '''Warning: Using old versions of Firefox poses a significant security risk.''' --------- If the latest version of Firefox is causing problems for you or you just don't like something about it, please give us feedback about it here: *https://input.mozilla.org/en-US/feedback/android? Thanks