Firefox 96.0 und 91.5.0 esr; Issues with web site access – but it's fixed now

[German]Mozilla developers have released version 96.0.0 with some new features and 95.5.0esr of the Firefox browser on January 11, 2022. However, with the new Firefox 96 there was problems accessing various websites. Here is the information on how to fix the access issues, caused by a (now fixed) telemetry http3 bug.

Firefox 96.0.0

According to the release notes, version 96.0 brings some new features as well as bug fixes and security fixes. The developers list the following as new features:

• Improvements made to noise reduction and automatic gain control, as well as slight improvements to echo cancellation to provide a better overall experience.
• The load on the main thread during browser execution has been significantly reduced.
• Firefox now sets all cookies with the SameSite=lax attribute by default, which helps protect against Cross-Site Request Forgery (CSRF) attacks.
• When printing, you can now choose to print only the odd or even pages.

Here's a rough overview of the bug fixes in the new Firefox, which the developers describe with the following notes:

• On macOS, links in Gmail now open in a new tab as expected when users click on a command.
• The latest version fixes an issue where videos are occasionally interrupted by SSRC
• The latest version also fixes an issue where WebRTC lowers the screen sharing resolution to provide a clearer browsing experience. 
• In addition, issues with video quality degradation on certain websites have been fixed.
• Disconnected video in full-screen mode on macOS has been temporarily disabled to avoid issues with corruption,

brightness changes, missing subtitles, and high CPU usage.
In addition, various vulnerabilities categorized as high have been fixed with the update. Using vulnerability CVE-2022-22743, an attacker can force the browser into full-screen mode without the user being able to exit it. Details about CVE-2022-22746 and other can be read on this Mozilla page. 

Firefox 91.5.0esr

An update of Firefox 91.5.0esr with one year of long-term support with the security fixes was also provided in each case.

The new Firefox and the ESR variants can be downloaded from this website for various platforms (the variant is to be selected via the list boxes displayed). 

Firefox 96 can not reach web pages

I had already seen it on Facebook the other night, and there's this German comment on the blog, and this tweet and this reddit.com post dealing with the issue. The browser simply cannot open various web pages anymore. The browser may also crash after minutes. For me, the browser currently just loads very long.

There is a Mozilla bug report, and the above tweet proposed a workaround:

If anyone need to fix it, please open "about:config" in a new tab.
Search : "network.http.http3.enabled"
change to false, then restart firefox.

German blog reader Frank contacted me by mail and writes:

Firefox96 definitely has a problem too, but I can't locate it yet.

After the update, Internet pages can no longer be opened properly.

With one customer it helped to install the version 96 again, with others not.

I am still looking for the cause. Unfortunately the customers are all impatient and want to continue working.
They are all desperately looking for the Internet Explorer, the reference to Edge then always brings a certain aha effect.

He had the hope that more users would contact Firefox with this problem. In a follow-up email he then still wrote:

What helped with us: In the Firefox settings, go to "Privacy & Security" and scroll down to "Data collection by Firefox." Uncheck the box for collecting telemetry data, i.e. "Allow Firefox to send data about technical details and interactions to Mozilla". After that, restart the browser.

But German users notified me, that the telemetrie bug has been fixed now.

Bug in telemetry fixed

log reader Daniel R. has now informed me on Facebook that the bug is probably fixed. In this Bugzilla thread it says:

Firefox has witnessed outages and we are sorry for that. We believe it's fixed and a restart of Firefox should restore normal behaviour. We will provide more information shortly

Status: NEW -> RESOLVED

Closed: 2 hours ago

status-firefox96: affected -> fixed

status-firefox97: affected -> fixed

status-firefox98: affected -> fixed

status-firefox-esr91: affected -> fixed

Resolution: — ->  FIXED

Seems that a bug within the telemetry that's using a broken http3 implementation was the cause – so let the telemetry disabled.