Is this a problem with extensions that have been disabled? Current Firefox releases require extensions to be signed to prevent abuse by malware. In Firefox 43 unsigned extensions will be disabled by default. You can set xpinstall.signatures.required to false to disable this security feature in Firefox 43. You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I'll be careful" to continue. *http://kb.mozillazine.org/about:config See also: *https://support.mozilla.org/kb/add-on-signing-in-firefox *http://www.ghacks.net/2015/12/16/what-you-do-when-firefox-disables-installed-add-ons/