Quote:

Mozilla has released Firefox 85.0.2, a stable channel update for the organization's Firefox web browser. Released for all supported desktop operating systems, Firefox 85.0.2 fixes an issue that is exclusive to certain devices running Apple's Macintosh operating system.

The official release notes are published already, stating that the new version of Firefox "fixes a deadlock during startup". The linked bug report on Bugzilla@Mozilla provides additional details about the issue.

The issue was reported two months ago. The reporter stated that the issue affected Mac OS Big Sur and Mac OS Caralina devices running Firefox., and that Firefox would hang when trying to launch a new window from the context menu using the icon on the Dock.
 

Quote:Steps to reproduce
Launch Firefox.
Try to open a new window from the context menu on the icon in Dock

Actual Result
Firefox is not responsible with rainbow cursor.
Firefox does not comeback and I need to quit Firefox forcely.
I reproduce this bug a few days ago.
I does not face this bug rarely on a new profile

The issue affected Firefox Nightly at the time but it seems to have been included in the beta and stable releases of Firefox 85 as well. Mozilla's update to Firefox 85.0.2 resolves the issue.

Firefox users may select Menu > Help > About Firefox to check the installed version and run a manual check for updates. Users whose version of Firefox is unresponsive may download the new release from Mozilla's official download site to install it manually after the download completes.

It looks as if the fix will also land in Firefox ESR, but it has not been released yet it appears. Mac users who run the ESR version of Firefox and experience the issue may monitor this link for changes.

Mozilla released Firefox 85.0.1 just three days ago to fix a critical security vulnerability in the browser. The next major release is Firefox 86 Stable; it is scheduled to be released on February 26, 2021.
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