This addon doesn't work properly - the tabs opened after restart are (very) different.
Also - and this is really bad - here is the list of permissions used. How can this be justified.

Access your data for all websites
Exchange messages with programs other than Firefox
Display notifications to you
Access browser tabs
Access browser activity during navigation

I don't know who Nacho Vázquez is, but judging by that list I don't trust him.
I'm about to uninstall, but I will repeat the tip given by mjjordan :
If you want a TRUE Firefox restart IN TWO CLICKS, do this:
1) Type about:restartrequired in your browser
2) Drag and drop that page to your toolbar
3) Click "Restart"

This addon does not restart the browser.

All I want is for this add-on to quit and start Firefox This add-on fails spectacularly in that respect.

ce module ne fonctionne pas toujours, il doit alors être désinstallé puis réinstallé pour fonctionner correctement

The author of this crappy extension is either a jerk or a con artist, as it doen't work at all, but make you go through a bunch of weird headaches. I wish I could give it 0 star. Stay away, it does not restart, and it's the worst extension ever in FF!!!

This does not "Restart" browser it merely "Refreshes" browser. There is a big difference.

再起動しません。
Do not restart

Stop looking for the Holy Grail of a usable restart button - they don't want you to have it !
BUT USE THIS INSTEAD : If you want a TRUE Firefox restart IN TWO CLICKS, do this:
1) Type about:restartrequired in your browser
2) Drag and drop that page to your toolbar
3) Click "Restart"
Done!
All credit to Andorio2007 - brilliant ! It works - no messing !

did not work FF 75.0 all I want is a button to click to restart browser and start with same tabs loaded like old firefox/waterfox/palemoon restart addon used to do. something simple, click a button/menu item and FF restarted.

Not working, I click on the icon and a message appears saying that there is no saved session

If you want a TRUE Firefox restart IN TWO CLICKS, do this:
1) Type about:restartrequired in your browser
2) Drag and drop that page to your toolbar
3) Click "Restart"
Done!

lol...just close and reopen :( memory no return

Disappointed. I want an icon, CLICK, and the browser shuts down and re-opens. When I lcick on the icon, a pop-up appears and tells me I don't have any saved sessions. Can't open Options.

Lo que hace realmente no es reiniciar el navegador, para eso está añadir a los marcadores esta página "about:profiles" (sin las comillas) o esta otra "about:restartrequired" (sin las comillas), pero esta extensión para bajar la cantidad de memoria que utiliza el navegador está muy bien. El mejor para mí es el método 2.
El método 1 también funciona pero tienes que preocuparte en grabar la sesión antes de apretar el botón. Gracias

What it really does is not restart the browser, for that it is to add to the bookmarks this page "about:profiles" (without the quotes) or this one "about:restartrequired" (without the quotes), but this extension to lower the amount of memory used by the browser is very good. The best for me is method 2.
Method 1 also works but you have to worry about recording the session before pressing the button. Thank you

https://i.imgur.com/cqNY06e.gifv

This button does nothing. Doesn't update browser

As others have said, it doesn't really restart the browser. Just closes the windows and reopens them.

The only reason I'm looking a plugin is because the default Firefox behavior is broken. In the best case scenario, I can exit Firefox. And then after re-opening it, have to immediately restore previous session from history. If I exit the browser twice in succession, my "previous" session is gone.

This plugin would have been great if it would have actually restarted the browser. But it doesn't. Not without some additional paid application.