Firefox 91 release overview

silversurfer

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Aug 17, 2014
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Firefox 91 release overview: new ESR base, Simplified Printing, new HTTPS-First Policy​

Executive Summary​

  • Firefox 91 is the new base for Extended Support Releases. It is supported for about a year with the released feature set.
  • Support for Windows single sign-on added.
  • HTTPS-First Policy in Private Browsing mode.
  • Firefox ESR 78.x is the last Firefox version that supports Flash officially. Support for it ends on October 10, 2021.
  • Firefox ESR 78.x is the last that supports Mac OS 10.12 or older.

New features and improvements​

HTTPS-First Policy​

Firefox will try to connect using HTTPS first when in private browsing mode. The browser falls back to HTTP only if a HTTPS connection is not available.

Firefox supports a HTTPS-Only Mode which users may configure to prioritize HTTPS always. The browser displays a warning page if HTTPS is not supported by a server. Options to use HTTP are then provided.

Firefox users who enable HTTPS-Only Mode in private browsing mode, or in all modes, get the same functionality.

Simplify Printing restored​

Mozilla introduced a new printing interface in Firefox 81. Simplified Printing, an option to turn the content into a bare-bones version optimized for printing, was removed in that update.

Simplified printing displays a version of the page based on the browser's Reader View feature. The focus is on the article and related content such as images; menus, advertisement, other blocks on the site are not displayed in the mode.

Firefox 91 restores the option, and you may once again select it in the print dialog.

firefox simplified printing
Other changes
  • Firefox supports signing-in to Microsoft work and school accounts using Windows single sign-on (on Windows, obviously).
  • Total Cookie Protection improvements that update the cookie clearing logic and reveal to users which websites are storing information locally.
  • New locale Scots (sco) added.
  • Firefox enables High Contrast Mode on Mac OS automatically if "Increase Contrast" is checked.
  • 10%-20% increase in most user interactions thanks to "catch-up paints".
  • New file downloading behavior. All downloads are saved to the default directory or selected directory, even if "open" is selected.
  • Switch to Tab results in Firefox's address bar in Private Browsing windows (previously only in regular browsing windows).

Security updates / fixes​

Security updates are revealed after the official release of the web browser. You find the information published here after release.
 

CyberTech

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Nov 10, 2017
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Anyone having this black screen issue on Firefox when tabs are opened in the background? It doesn't happen always, but it's happening quite often for me. It's not related to the new version 91. It was happening in 90 too. Tabs come into view only after scrolling.
Edit: Tagging some users who I know regularly use Firefox. @harlan4096 @plat1098 @SecureKongo
View attachment 260125

No issue for me, did you try it in private window mode? and disable any addons and try to see it..
 

rain2reign

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Jun 21, 2020
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Anyone having this black screen issue on Firefox when tabs are opened in the background? It doesn't happen always, but it's happening quite often for me. It's not related to the new version 91. It was happening in 90 too. Tabs come into view only after scrolling.
Edit: Tagging some users who I know regularly use Firefox. @harlan4096 @plat1098 @SecureKongo
View attachment 260125
Cant say I have come across that issue, fortunately.
 

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