Best would be to install Firefox 48 on that new computer and then update to the current release in one or more stages. That way possible migrate code can do its job and properly update all files to the currently used version and the risk of dataloss is much lower. *https://download-origin.cdn.mozilla.net/pub/firefox/releases/48.0.2/mac/en-US/ See also: *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the <b>about:profiles</b> page. *Help -> Troubleshooting Information -> Profile Directory:<br>Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder *http://kb.mozillazine.org/Profile_folder_-_Firefox ---- You can find the full version of the current Firefox release (60.0.2) in all languages and all operating systems here: *https://www.mozilla.org/en-US/firefox/all/ *https://www.mozilla.org/en-US/firefox/60.0.2/releasenotes/