Mozilla releases updates to Firefox Stable regularly. The organization did so on a six week schedule in the past, but has loosened that up a bit in recent time.
This schedule bumps the number in front of the dot by one. Smaller updates may increase the number after the dot to fix smaller issues or introduce changes to the browser.
Firefox Beta, Developer and Nightly versions are updated more frequently than the stable version.
Firefox updates should not have any impact on a user's custom configuration of the browser. There are a couple of exceptions to the rule. One is, if Mozilla decides to remove a preference from the browser, or rename it.
Beware! Firefox updates may reset preferences
I was contacted by two Ghacks readers in the past two weeks about Firefox resetting preferences of the web browser during updates.
Basic protection is the recommended and default value of the setting. It does not block as many trackers as the strict blocking list.
I confirmed that the upgrade to Firefox 50 did indeed reset the preference.
Michel told me a week later that a recent Firefox update (to 50.0.1 or 50.0.2) did reset another preference. This time an URL string that Michel modified on Firefox's about:config page.
As you may know, you can modify hundreds of preferences on about:config. Some allow you to change URLs that Firefox uses. In this particular case, Michel modified the URL responsible for pulling add-on suggestions on the about:addons page of the browser.
And it was this URL that reset when Firefox updated to one of the newer versions.
The two users noticed the changes because they impacted how they use the browser. While those two are confirmed -- I confirmed the resetting using a local copy of Firefox -- there is no telling if other preferences were also reset in recent time during updates.
I can't come up with reasons why resetting those two preferences was justified.
As I said earlier, it may make sense to reset preferences for a variety of legitimate reasons. This should only happen however if it does not impact a user's customization provided that it is still valid.
Since both basic and strict protections are still available, and since it is possible to change the URL of the add-ons suggestions page, I'm puzzled why the preferences were reset.
Now You: Did you notice the resetting of Firefox preferences during updates?