Why can't I install some add-ons from addons.mozilla.org?
When I want to install an add-on I tap on "Tools" -> "Add-ons" -> "Browse all Firefox Add-ons" which opens a new tab for https://addons.mozilla.org/de/android where I search for an add-on I want and then tap on it. Now I tap on "+ Add to Firefox" and it says "Blocked add-on Firefox prevented this site (addons.mozilla.org) from asking you to install software on your device" that shouldn't happen in the first place. I then can choose "dismiss" or "allow" so I tap "allow " and with some add-ons it then says "downloading addon" -> "Installing Add-on (name of the add-on)|cancel|install" which is fine, but for other add-ons e.g. https://addons.mozilla.org/de/android/addon/bookmark-all-tabs/ it first says "downloading addon" and then "Blocked add-on|firefox has prevented addons.mozilla.org from installing an unverified add-on android|learn more". So I tap on "learn more" which opens https://support.mozilla.org/1/mobile/49.0/android/de/unsigned-addons where I am told that "All add-ons hosted on addons.mozilla.org are signed before they are listed." which isn't helpful.
Todas as respostas (1)
As of Firefox 46 extension signing is mandatory. https://www.mozilla.org/en-US/firefox/android/46.0/releasenotes/
The 'Bookmark All Tabs' extension has been published back in 2013. It apparently hasn't been updated since, and isn't compatible anymore with recent versions of Firefox. Looks like the extension has been abandoned by it's author.
Also, when you look at the add-ons page on AMO: https://addons.mozilla.org/en-US/android/addon/bookmark-all-tabs/
Underneath 'Version Information': Only available on Firefox Desktop