Hi, I recently upgraded to Firefox 39 (I always upgrade as updates become available). However, as a result of the upgrade all of my Add-Ons disappeared. There is a folder on my desktop entitled Old Firefox Data which I presume contains details of the previous installation, including the Add-Ons. Is there some way to automatically reinstate the Add-Ons, or do I have to manually download and re-install them? I appreciate that some of the Add-Ons may not be compatible with current version of Firefox, but conversely some of them will still be compatible.