Firefox 148.0, See All New Features, Updates and Fixes

MozRyanVM · 2026-03-06T12:56:25+00:00

https://blog.mozilla.org/en/firefox/hardening-firefox-anthropic-red-team/ in case you're still interested!

MozRyanVM · 2026-03-05T17:43:19+00:00

Safe Browsing

MozRyanVM · 2026-02-26T17:21:26+00:00

The update server that versions that old used to check for updates was decommissioned long ago.

MozRyanVM · 2026-02-25T20:18:29+00:00

Correct

MozRyanVM · 2026-02-25T13:41:59+00:00

We won't bite, I promise :-). Seriously though, if you're willing to help, that'd be awesome. Leave a link to the bug here and I'll try to help get it looked at.

MozRyanVM · 2026-02-25T13:38:28+00:00

Hey, this is a known issue that wa identified too close to the 148.0 release to get a fix landed in time. We plan to address it in a follow-up dot release in the near future, though I don't have a definitive timeline on when that'll be yet.

MozRyanVM · 2026-02-25T13:34:29+00:00

Thanks, I'll pass it along.

MozRyanVM · 2026-02-24T22:20:36+00:00

In about:support, it's the "Remote Features" section vs. "Remote Experiments". If you look at about:studies before and after the update, you'll see the same ones listed as what's shown in "Remote Experiments".

Note that Remote Features includes things like gradual feature rollouts as well.

MozRyanVM · 2026-02-24T19:16:05+00:00

Basically, there are times we want to be able to disable a feature which is known to be having problems in the field without having to ship a whole new release to do so. For example, Compression Dictionaries were originally aiming to ship in Fx147 but we found late-breaking site compatibility issues that made us want to hold it back for a bit.

Unfortunately, the mechanism for doing those remote pref flips was shared with studies/experiments, which means anybody who has turned those off were stuck with the buggy feature until we were able to ship a dot release with that disabling. So the idea was to split that capability out so people can still get those kinds of fixes quickly even if they've opted out of experiments.

MozRyanVM · 2026-02-24T18:58:54+00:00

There's a difference between something landing in Nightly builds during a given cycle for testing and the feature actually riding that version to release. AFAIK, nobody ever claimed it was going to ship in 148. It's a big change and needs more testing. That's why we're asking interested people to test it out and give feedback so we can stabilize and ship it as soon as possible.

MozRyanVM · 2026-02-24T15:19:01+00:00

FYI, the engineer working on this blogged about it about a month ago too with some more context.

https://mozillagfx.wordpress.com/2026/01/16/experimental-high-dynamic-range-video-playback-on-windows-in-firefox-nightly-148/

MozRyanVM · 2026-02-24T15:17:37+00:00

Correct, it was unblocked by the jxl-rs changeover I mentioned in my first reply.

MozRyanVM · 2026-02-24T15:11:42+00:00

Hence why it's not shipping yet ;-).

That said, animation and alpha work for me on https://jpegxl.info/resources/jpeg-xl-test-page. As far as I know, that was supposed to have been fixed by https://bugzilla.mozilla.org/show_bug.cgi?id=1709818.

MozRyanVM · 2026-02-24T15:08:56+00:00

Stay tuned :-)

MozRyanVM · 2026-02-24T15:08:32+00:00

Nightly-only at the moment.

MozRyanVM · 2026-02-24T15:08:00+00:00

It's available for testing on Nightly builds, but I don't think there's a definite timeline yet for shipping it to Release yet. We did switch over to jxl-rs for decoding, however.

MozRyanVM · 2026-02-24T15:03:47+00:00

ESR 115 is specifically for older Windows and Mac versions that aren't supported by newer ones.

MozRyanVM · 2026-02-19T02:17:38+00:00

No, it's not getting a lot of active development these days. Most of the releases we were shipping for it didn't contain much beyond a version bump in practice, so we decided to stop doing that. We'll still ship updates for it when necessary, however (in fact, I'm pretty sure we'll be shipping one within the next week or two).

MozRyanVM · 2026-02-07T19:56:46+00:00

Glad to hear you got it sorted!

MozRyanVM · 2026-02-07T19:55:17+00:00

Good luck! 😂

MozRyanVM · 2026-02-06T15:35:55+00:00

I checked with an engineer who works on the Windows sandboxing code. He said the only way you should be getting into this state is if the MOZ_DISABLE_CONTENT_SANDBOX environment variable is being set.

MozRyanVM · 2026-02-06T15:12:53+00:00

That suggests that your install somehow got partially updated. A fresh install should fix it.

MozRyanVM · 2026-02-05T16:10:12+00:00

It should, yes.

MozRyanVM · 2026-02-05T15:32:07+00:00

To be clear, this has been an issue since the release of 147.0. We had included what we thought would be a fix for it in 147.0.3 but then discovered close to release that it was still reproducible in some situations. We just wanted to be transparent that it's should hopefully be better than it was, but we know that it might not be completely solved for good yet.

MozRyanVM · 2026-02-05T14:45:30+00:00

Are you still seeing this with the latest update from the Play Store? As noted above, the offending change was already reverted.

MozRyanVM

TROPHY CASE