Add Firefox ESR (Extended Support Release) support statement for latest release

[MikeMcC399]

Description

What would you like?

Include an official statement of support by Cypress for the latest Firefox ESR (Extended Support Release), in addition to the latest 3 major versions from the Firefox Rapid Release channel.

Why is this needed?

Firefox ESR is the only stable Firefox release which supports both the Linux/amd64 and the Linux/arm64 platforms on Debian-based distributions. Cypress Docker images are based on Debian 12 which includes Firefox ESR as its default browser: for instance Debian 12.9 currently includes Firefox ESR 128.8.0esr.

References > Lauching Browsers > Browser versions supported currently states:

Cypress officially supports the latest 3 major versions of Chrome, Firefox, and Edge. (For example, if the stable release of Chrome was 130, Cypress would officially support Chrome 128, 129, and 130.)

The current latest major version of Firefox is 136 138 (see Firefox release notes).

So, according to the Cypress text above, Firefox 134, 135 136, 137 and 138 would be supported by Cypress.

The latest Firefox ESR version is however 128, which is outside the rule covered by "latest 3 major versions". See https://www.mozilla.org/en-US/firefox/organizations/notes/. Firefox 128.0esr was released on Jul 9, 2024.

Although Cypress 14 runs successfully against Firefox 128 ESR on Debian, according to the documentation, it is not officially supported by Cypress.

Other

Choosing a Firefox update channel explains the Firefox "Extended Support Release (ESR)" and compares it to the "Rapid Release" channel.

Extended Support Release (ESR): receives major updates on average every 52 weeks with minor updates such as crash fixes, security fixes and policy updates as needed, but at least every four weeks.

Debian 12 test

On Debian 12.9 amd64, Node.js 22.13.0 LTS, the following test runs successfully, so I assume that adding support for Firefox ESR is a documentation change only and that it does not need a feature request in the https://github.com/cypress-io/cypress repo:

sudo apt-get update && sudo apt-get install firefox-esr -y

git clone https://github.com/cypress-io/cypress-docker-images
cd cypress-docker-images
cd examples/firefox-esr

npm install cypress@14 -D
npx cypress info
npx cypress run --browser firefox

[MikeMcC399]

This request will need to be revised, since Firefox 136.0 announced:

On Linux, Firefox is now available on ARM64 (AArch64), with installation options via APT and tarballs. Flatpak support is coming soon.

The argument about Firefox ESR being the only Firefox version that runs on ARM64 no longer holds true. There may however be organizations that use and rely on Firefox ESR, meaning that Cypress may be needed to test in this environment.

[MikeMcC399]

Firefox ESR 140
Firefox 140 is the next ESR and will be released on June 24, 2025.

[jennifer-shehane]

@MikeMcC399 What's your suggestion here now?

[MikeMcC399]

@jennifer-shehane

What's your suggestion here now?

I think now, wait until both Cypress 15 and Firefox ESR 140 are released and then decide if Firefox ESR 140 should be mentioned as a long-term-supported item.

Don't make any new statement for Firefox 128 ESR anymore. It seems to work fine, but on the other hand Firefox has regularly been the source of breaking changes, so maybe it would be good to start with a new baseline at Firefox ESR 140 without having to worry about Firefox 128 ESR.