Every day I turn my laptop on, launch Firefox, and the tab opens that says this add on has been updated. And my saved accounts are gone.
I finally got smart and exported my data so every day I just import it. But it's highly annoying. There isn't a new version of this add on every day. Why is it doing this? So frustrating.
Reinstall
This has happened to others before... the usual fix is to simply reinstall it.
Updates to new every day...
I have the same problem... Firefox 54.0 (64-bit) with X-notifier 4.0.3.
Every time that I launch Firefox, X-notifier gets automatically re-installed and wipes out all my email accounts!
I have manually uninstalled and re-installed X-notifier several times without success. And, yes, every time that I manually reinstalled X-notifier and re-created my email accounts, I made sure to press the Save button...
What I have resorted to doing is I exported my email accounts information into a password-protected file (firefox.xn). Every time that X-notifier gets re-installed, I re-import the email accounts from the file. But I would not call this a good solution to the problem...
X-notifier 4 relies on cookies
The fact you get that update confirmation page doesn't perse mean the addon got reinstalled.
The fact your settings get lost can mean you have set to delete cookies when Firefox restarts.
http://xnotifier.tobwithu.com/dp/node/3353 (scroll down)
Updates to new every day
Thanks, jeroen! At least X-notifier 4.0.3 no longer re-installs itself every time that Firefox is launched.
Now if I could get Yahoo!Mail to work... I see that somebody has come up with a solution for v. 3.5.x. Hopefully, somebody will do the same for v. 4.0.3.