Is that by searching via the about:addons page or by searching the AMO website (addons.mozilla.org) ?

Thanks. I found a way to install the Extensions I needed through Mycroft Project. All Extensions now working perfectly. Background - Firefox was working extremely slow & was not completing links. I uninstalled Firefox & re-installed. The latest Version was an immediate improvement. However, my Anti-Virus Extension would not load to Firefox. I had to allow Remote Access so that they could fix the issue. Resolved. While I watched them fix it I noticed that some Certificates were missing. Somewhere something had gone amiss in the Firefox installation. Whether that is a lingering problem I do not know. But suggestions to fix the Add-ons search problem would be appreciated. Regards Chris PS Both Firefox methods to search Add-ons were used & failed.