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Firefox Beta and Developer Edition
Release Notes

Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.

66.0beta Firefox Beta

January 29, 2019

Version 66.0beta, first offered to Beta channel users on January 29, 2019


  • Increased content processes to 8

  • Added capability to search through open tabs from the tab overflow menu

  • New backend for the storage.local WebExtensions API, providing I/O performance improvements when the extension updates a small subset of the stored data

  • WebExtension keyboard shortcuts can now be managed or overridden from about:addons

  • Improved scrolling behavior: Firefox will now attempt to keep content from jumping around while a page is loading by supporting scroll anchoring

  • New about:privatebrowsing with search

  • Basic macOS touchbar support

  • A certificate error page now notifies the user of the name of the certificate issuer that breaks HTTPs connections on intercepted connections to help troubleshooting possible anti-virus software issues.


  • Fixed an performance issue some Linux users experienced with the Downloads panel (bug 1517101).



  • It is now possible to select new elements in the page while the debugger is paused

  • JavaScript getters can now be executed from the auto-completion popup in the WebConsole

  • window.alert()/prompt()/confirm() now works again in Responsive Design Mode

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