The Windows version of Firefox can now automatically upgrade itself to the latest version in the background when the web browser is not running.

"Background Update is now available on Windows. This feature will allow Firefox to update, even if it is not running," the Firefox 90.0 Beta release notes read.

"Until now, Firefox has only downloaded and installed updates when the user runs it. This means that users that use Firefox infrequently are often out-of-date," according to Kirk Steuber, Platform Engineer at Mozilla.

"It also means that if they open Firefox again in response to a marketing campaign, they may not immediately get the features advertised.

"Background Update aims to address this problem by allowing updates to be downloaded and installed, even when the user doesn't run Firefox."

How the background update feature works 

Firefox background updates will be scheduled for the default profile every 7 hours when the browser is not running to check for new updates, download them, and install them without requiring user interaction.

The underlying mechanism behind the OS-level scheduled update tasks is Firefox running in a stripped-down headless "Background Task Mode."

While you are using Firefox, the headless Firefox process will not check for updates to avoid affecting the user experience by inadvertently forcing restarts.

"If you need to disable this functionality, about:preferences should show a checkbox in the 'Updates' section for you to disable, or you can set the BackgroundAppUpdate Firefox policy to false," Mozilla's Nick Alexander said.

Rolling out to all Windows users

This new feature was first rolled out to Windows Nightly users on April 12 in the form of a Background Update Agent.

Background Update is now part of a staged rollout to all Windows users over the next few months, as part of the Beta 89 and the Release 89 cycles.

However, Mozilla first announced that the feature was under development more than four years ago as a background process designed to check for updates and apply them for users with slow Internet connections and/or who don't run Firefox daily.

While background updates have already been announced for Windows, there are no immediate plans to implement the feature for macOS and Linux.

On a related note, Firefox also installs an optional service named Mozilla Maintenance Service that only launches in the background when updates are downloaded.

This service is designed to allow updates to be installed without requiring the user to click "Yes" in the Windows User Account Control (UAC) dialog.