If you want to mange add-ons then you can click one of the other tabs like Extensions or Plugins.<br /> It can happen more often the the Get Add-ons Tabs is not responding or takes a long time. If the Extensions tab still doesn't show the Extension then it is possible that there is a problem with the file(s) that store the extensions registry. Delete the extensions.* files (e.g. extensions.sqlite, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry. *https://support.mozilla.org/kb/Profiles New files will be created when required. See "Corrupt extension files": *http://kb.mozillazine.org/Unable_to_install_themes_or_extensions *https://support.mozilla.org/kb/Unable+to+install+add-ons If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left end side of the Search Bar ("Find Updates" button in older Firefox versions) to check if there is a compatibility update available. If this hasn't helped then also delete the addons.sqlite file.

Seems to have worked (not knowledgeable enough to know if there are other repercussions to my actions--yet). Thank you.