I have Mac. I have Firefox 38. I've been asked to update to 3.9, then to 4.0. I download the package and tell it to install it. It never completes.
I am continually asked if I want 40. I say yes. It's downloaded and then asks me to click to install. I click. Firefox restarts, but it never updates from 38. I've done this at least 20 times over the last two months.
Wšykne wótegrona (1)
If there are problems with updating or with the permissions then best is to download the full version and trash the currently installed version to do a clean install of the new version.
Download a new copy of the Firefox application and save the disk image file to the desktop
- Firefox 40.0.3: https://www.mozilla.org/en-US/firefox/all/
- Trash the current Firefox application (open the Applications folder in the Finder and drag the Firefox application to the Trash) to do a clean (re)install
- Install the new version that you have downloaded
- https://support.mozilla.org/kb/Installing+Firefox+on+Mac
Your personal data is stored elsewhere in the Firefox profile folder, so you won't lose personal data like bookmarks when you uninstall and (re)install or update Firefox.