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It should update I would think to the Final version on Nov 14th.

Only way I know is to uninstall and to reinstall Firefox 56.0.2 is current release https://www.mozilla.org/firefox/all/ Full Version Installer

You could try and trouble shoot the plugin : https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems?redirectlocale=en-US&redirectslug=Troubleshooting+extensions+and+themes

Please let us know if this solved your issue or if need further assistance.

Is the non-working add-on a Legacy extension? Could you mention which one it is in case there is a known good substitute?

You can switch from the "beta" release to the current "stable" release, which is Firefox 56.0.2. Normally this kind of change is seamless -- the installer detects your existing data and preserves everything, subject to possible changes in your data files that can't be rolled back -- but you might want to make a backup "just in case."

• Back up and restore information in Firefox profiles
• Full installers for the stable release: https://www.mozilla.org/firefox/all/

Thank you both for your time, both answers make sense. My problem is that Lastpass doesn't work with the new version yet. I think I will use Chrome until the 14th and in the mean time contact Lastpass to see when they will have a plug-in for the new!

LastPass has a blog post on its plans for Firefox 57 here:

https://blog.lastpass.com/2017/10/lastpass-beta-firefox-57.html/

There appear to be some problems with the beta version:

https://forums.lastpass.com/search.php?keywords=firefox