CentOS replaced well-running customise Firefox with version ESR 45.1.0
* All the add-ons (language dictionaries, Adblock Plus, Classic Theme Restorer etc.) were disabled with no simple method of reactivating them. Reason given was they were “unsigned”.
xpinstall.signatures.required = false partially reduced the problem.
* Then possible to reactivate some disabled add-ons, but others down-loaded OK but would not install
* removing files in ~/.mozilla/firefox/…/extensions.* and restarting was supposed to help
However the time-wasting problem remains, so too do the down-loaded extensions in /tmp, example tmp-xxx.xpi
Would be really nice if CentOS warned its loyal and grateful users of possible problems before those users trustingly replaced working programmes with considerable time-wasting problems.
Time spent on trying to return Firefox to a useful and dependable working tool is unavailable for other tasks :-(