It's possible that it is something in the way Ubuntu rolled it, but it could just be a stuck pref. Had you tried changing it to another directory, and then back? Or change to always ask, and back? You can also check by typing '''about:config''' in the address bar, Enter, then search '''browser.download.useDownloadDir''' and toggle this to True (even if it already says true, toggle it twice). Mine was sticking to the browser.download.lastDir setting from when i chose a different directory once. But then, it always shows the save file dialog... which is not correct behaviour, i think. That is the same as always ask... even if it defaults to the correct directory. Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:71.0) Gecko/20100101 Firefox/71.0 (Mint XFCE)