LibX and Zotero 4 will stop working after the upgrade.
Firefox 57 was released Tuesday, November 14, 2017. This upgrade involved a complete change of the framework of how add-ons work in Firefox. Legacy extensions that are not built with the WebExtension API will no longer work after the upgrade.
Windows, macOS, and Linux users will all be affected if the extensions they are currently using do not have updates.
Users should upgrade to Zotero 5, which is a stand-alone application – once installed, you select a connector (a browser add-on) for whatever browser you use. There is no workaround available because it is no longer technically possible for Zotero 4 to run on Firefox's new add-ons framework.
What should I do if I am currently running Zotero 4 on Firefox?
Install the Zotero Connector for Firefox from the Zotero download page, which will replace Zotero 4.0 for Firefox.
From the same download page, install Zotero 5.0 for your operating system (Mac, Windows, or Linux).
You can also install the Zotero Connector in any other browsers that you use.