Introduction

Mozilla has rolled out Firefox 145, a significant update that brings a range of usability, security and privacy enhancements, while marking a clear turning point by discontinuing official support for 32-bit Linux systems. For users on older hardware or legacy distros, this change means it’s time to consider moving to a 64-bit environment or opting for a supported version.

Here’s a detailed look at what’s new, what’s changed, and what you need to know.

Major Changes in Firefox 145

One of the headline items in this release is Mozilla’s decision to stop building and distributing Firefox for 32-bit x86 Linux. As per their announcement:

“32-bit Linux (on x86) is no longer widely supported by the vast majority of Linux distributions, and maintaining Firefox on this platform has become increasingly difficult and unreliable.”

From Firefox 145 onward, only 64-bit (x86_64) and relevant 64-bit architectures (such as ARM64) will be officially supported. For those still running 32-bit Linux builds, Mozilla recommends migrating to 64-bit or switching to the Extended Support Release (ESR) branch (Firefox 140 ESR) which still supports 32-bit for a limited period.

Firefox 145 brings several improvements designed to make everyday web browsing smoother and more flexible:

• PDF viewer enhancements: You can now add, edit, and delete comments in PDFs, and a comments sidebar helps you easily navigate your annotations.

• Tab-group preview: When you hover over the name of a collapsed tab group, a thumbnail preview of the tabs inside appears, helpful for reorganizing or returning to work.

• Access saved passwords from the sidebar, without needing to open a new tab or window.

• “Open links from apps next to your active tab” setting: When enabled, links opened from external applications insert next to your current tab instead of at the end of the tab bar.

• Slight UI refinements: Buttons, input fields, tabs and other elements get more rounded edges, horizontal tabs are redesigned to align with vertical-tab aesthetics.

Mozilla has also doubled down on privacy and risk reduction:

• Fingerprinting defenses: Firefox 145 introduces new anti-fingerprinting techniques that Mozilla estimates reduce the number of users identified as unique by nearly half when Private Browsing mode or Enhanced Tracking Protection (strict) is used.

• Enhanced Bounce Tracking Protection: The stateless mode for bounce tracking is now enabled by default under ETP Strict.

• New web platform support: For developers and advanced users there’s support for the Atomics.waitAsync proposal, the Integrity-Policy HTTP header, and expanded Matroska container support (AVC, HEVC, VP8/VP9, AV1, AAC, Opus, Vorbis) in the built-in media player.

What This Means for 32-Bit Linux Users

If you’re currently using a 32-bit Linux system (x86), here are the implications:

• Firefox 144 (and Firefox 140 ESR) are the last versions supporting 32-bit on Linux. From version 145 onward, you will not receive updates or fixes on 32-bit builds.

• If you continue using Firefox 144 on 32-bit, you should plan a migration:

  • Move to a 64-bit operating system on supported hardware if possible.

  • Alternatively, switch to Firefox 140 ESR (if your distro or environment allows) to receive security updates longer.

• For embedded systems, older PCs or legacy use-cases still on 32-bit: explore alternate browsers that still support 32-bit, or assess hardware upgrade options.

Upgrade Advice & How to Get Firefox 145

• Firefox 145 is available for download starting November 11, 2025.

• For Linux distros:

  • Check your package manager or distribution’s repository for the update.

  • Ensure you’re on a 64-bit build of your OS.

  • For distributions providing 32-bit support, note that future Firefox updates won’t arrive; consider migrating or switching browsers.

• For Windows/macOS and ARM64: The release also applies, but the big change for Linux is the dropped 32-bit support.

Final Thoughts

Firefox 145 is more than just another version, it marks an important shift in how Mozilla manages platform support, focusing on modern architectures and dropping legacy 32-bit Linux builds. Coupled with meaningful improvements in PDF tools, UI refinements and stronger privacy protections, it’s a worthwhile upgrade for most users.

If you’re still on 32-bit Linux hardware, now is the time to plan. Because yes, the era of 32-bit Linux builds for Firefox is officially over.