After having a lot of issues I have found it is related to having Firefox not remember my history, this seemed to have cause the extension not to accept master password.
Now working as it has for the past 5years, still my favorite, down voted due to the Firfox issue.

Small Frustrations
The extension is great and I can understand the reason for some of the things which cause frustration. But it would be nice if you could designate a "home" computer which would stay logged in at all times. It may be only once every 30 days but each time I consider uninstalling the extension.

Giving you an unknown error? Try accessing through a different browser and changing your master password. Worked for me.

Depuis la mise à jour, le mot de passe maître est refusé, le changer à nouveau ne change rien... Lastpass est donc inutilisable

Works well for me, does have trouble finding the username/password fields on some pages, but some websites are very broken.

Easy to use and I like the complementary Android app as well

Nutze LastPass seit vielen Jahren und bin vollkommen zufrieden.