Firefox 156 is out: update your desktop browser and verify the version

Image: Firefox desktop marketing screenshot (Mozilla).

If Firefox is your daily browser on a Windows, Mac, or Linux computer at home, take a few minutes today and move onto Firefox 156. Mozilla released 156.0 to the Release channel on September 15, 2026. The official notes are on Firefox 156.0 release notes.

This is a normal major train for everyday desktop users. Install the update, fully quit and relaunch, then prove the running build with about:support. (Skip the separate Firefox for Enterprise notes unless you manage locked-down work browsers.)

What is new enough to notice at home

From Mozilla’s 156.0 notes:

Faster PDF startup. Firefox’s built-in PDF viewer now starts up to 45% faster. If you open bank statements, manuals, or school forms inside the browser, that is the change you may feel first.
Large scaled-down JPEGs. Memory and CPU use improve when Firefox shows large JPEG images scaled down to fit a page. Photo-heavy sites and long articles with big hero images should lean on the machine less.
macOS launch at startup. On Mac, you can set Firefox to open automatically when the computer starts, from the Startup section of Settings. Handy if Firefox is your default and you want it waiting after login. Skip it if you prefer a clean desktop until you click the icon.
Firefox Suggest in France, Germany, and Italy. Localized Wikipedia suggestions and occasional sponsored suggestions in the address bar are now available in those countries. You can turn them off in Firefox Suggest settings if you do not want them.
Security fixes. The notes include the usual “various security fixes” line. Treat that as a reason to update even if none of the feature bullets excite you.

There are also everyday bug fixes in the notes (Picture-in-Picture subtitles, bookmarks sidebar drag quirks, DoH edge cases, and more). Read the full list on Mozilla’s page if something you hit last month sounds familiar.

Update Firefox on your computer

Open Firefox on the computer you actually browse with.
Check for updates.
- Windows / Linux: Menu (three lines) → Help → About Firefox.
- macOS: Firefox menu → About Firefox.
Stay on the About window until the download finishes. Firefox often says it is downloading or ready to restart.
Restart to update when prompted. Do not click Later and keep working in old windows.
Fully quit if the version still looks old. Close every Firefox window. On Windows, confirm in Task Manager that no firefox.exe helpers are left. On Mac, use Firefox → Quit Firefox. Then open Firefox again.
Verify with about:support. Type that into the address bar. On the Application Basics block, read Version. You want 156.0 (or a 156.0.x dot release if Mozilla ships one soon after).
Repeat on other home computers that still run Firefox, including a laptop that stays open for days and any shared family machine.

If About Firefox says an update is coming but will not offer 156 yet, wait for your Release roll to reach you, then force the check again. Mozilla stages Release over time the same way other browsers do.

You can also download a fresh installer from Mozilla’s site if a stuck profile update loop refuses to move. Prefer Mozilla’s own download links over random “Firefox offline installer” pages.

Do not stop at “it said updated”

Do not assume a Windows reboot alone applied Firefox 156 if about:support still shows 155.x or earlier.
Do not leave old Firefox windows or background helpers running after an update prompt. Those keep the old build alive.
Do not skip the about:support check because the About window looked green. The support page is the proof of the running process.
Do not assume updating Firefox also updated Chrome, Edge, Brave, or Safari. Update each browser you actually use.

Optional toggles after you land on 156

macOS startup: Settings → Startup if you want Firefox to launch at login.
Suggest: If you are in France, Germany, or Italy and the new address-bar suggestions feel noisy, open Firefox Suggest settings and turn them off.
PDF habit: Try opening the next PDF in the tab instead of downloading to a separate app. The faster viewer startup is wasted if you always “Open with Preview” out of habit.

Bottom line

Firefox 156.0 hit the Release channel on September 15, 2026 with a faster PDF viewer (up to 45% quicker startup), better behavior on large scaled-down JPEGs, a macOS launch-at-startup setting, Suggest availability in FR/DE/IT, and security fixes, per the official release notes. On your home PC or Mac: open About Firefox, install, fully quit and relaunch, then confirm about:support shows 156.0. That is the whole job.