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With firefox-46.0-2.fc25, when starting the browser, my add ons don't seem to be enabled even though they show enabled in the about:addons page. Examples include uMatrix, https-everywhere and uBlock-origin. If I go and disable them, then enable them they appear in the menu bar and seem to work. Restarting brings them back to not being active. All of these addons are installed in my account, not system wide and are as far as I know signed.
Actually, https-everywhere starts normally... it's just others that don't.
Trying firefox-46.0-2.fc23.x86_64 on a system with fr_FR as local, Firefox UI stays in enfglish. File langpack-fr.org.xpi is present in /usr/lib64/firefox/langpacks and french is enabled in preferences I tried with no success to force general.useragent.locale to fr-FR
Should be fixed in firefox-46.0-3 which is in koji now.
Bingo ! I just installed firefox-46.0-4.fc23.x86_64.rpm from koji. It fixes both translation problem and add-ons error messages at startup. Thanks for your effort.