Extensions in Firefox 85

Before we get into the updates coming to Firefox 85, I want to highlight two changes that we uplifted to Firefox 84, now on release:

• Expose HTTPS-Only preference in privacy.network. Firefox now has a setting to enable HTTPS-Only Mode, which can conflict with extensions like HTTPS Everywhere. This change allows extensions to monitor the setting’s value.
• The webRequest and proxy APIs will now be able to observe requests made through the View Source feature of Firefox.

Now, back to our regular programming. Here’s what’s coming in Firefox 85, which is scheduled to be released on January 26, 2021:

• It is now possible to disable a homepage and new tab override for an extension without disabling the extension. Special thanks to Erica Wright for getting this done.
• The “Undo Close Tabs” feature now does the right thing if an extension just closed multiple tabs.
• The browsingData API is now available on Firefox for Android.
• Certain errors triggered when an extension changes a permission to optional during an update have been fixed.
• When the devtools permission is revoked and then granted, extension pages are now automatically enabled in the toolbox.

And finally, we want to remind you about upcoming site isolation changes with Project Fission. As we previously mentioned, the drawWindow method is being deprecated as part of this work. If you use this API, we recommend that you switch to the captureTab method.

About 15% of users on Nightly currently run with Fission. If you see any bug reports that you can’t replicate, remember to test with Fission enabled. Instructions for enabling Fission can be found on the wiki.

Thanks

Big thanks to Liz Krane, Ankush Dua, and Michael Goossens for their contributions to this release!