Along with other innovations like the multi-process architecture, Google Chrome introduced a new update model that minimizes user interaction and delivers the newest, most stable and secure version to the users quickly and silently, in the background. In this regard, Chrome is almost like a web application, where users run the newest version from the server without seeing version numbers or update prompts. A very interesting study conducted last year showed it’s the most efficient system currently available and their conclusions are pretty straightforward:
Our measurements prove that silent updates and little dependency on the underlying operating system are most effective to get users of Web browsers to surf the Web with the latest browser version. [...] We recommend any software vendor to seriously consider deploying silent updates as this benefits both the vendor and the user, especially for widely used attack-exposed applications like Web browsers and browser plug-ins.
I was a little surprised to discover that Firefox also has a silent update option, but it’s not turned on by default. To enable it, visit the about:config page, search for the entry app.update.silent and double-click it to change the value to True. You must also have the preferences app.update.enabled and app.update.auto set to true, but these are the default values, so you don’t have to worry about them. With silent updates enabled, Firefox will stop prompting you when it finds a new version; it will download the update in the background and install it when the browser restarts.
If you want more control over the updates even with this silent option turned on, there is another preference you can tweak: app.update.mode. The default value is 1, meaning the browser will “automatically download updates for minor and major releases, if no incompatibilities with addons are present, otherwise prompt”. With silent updates turned on, the browser will not be updated if one of your extensions is incompatible, so you could use this if you want to wait until all your extensions are also updated. If you opt for more security and want a more up-to-date browser, use 0, “automatically download updates for minor and major updates, regardless of incompatibilities that may arise with addons” or 2 “automatically download updates for minor releases, prompt about major releases” instead.
Unfortunately, there is no matching user preference for extensions updates. I have tried creating an entry called extensions.update.silent, but it didn’t have any effect. Ironically, the solution may be another add-on, Update Notifier, mentioned in the Mozilla Support forums.
This silent mechanism was already around for a while in Firefox and Thunderbird, at least since version 1.5. While the silent model is clearly better at keeping software updated with the latest versions, Mozilla probably wants to let the users have the final choice over the moment of update.