I can't find any instructions on how to use this extension. When i tried using my "master" password (so long, since it has to be at least 12 clicks long), I couldn't sign in to one of my sites. I had to use my old, site-specific password.

This shouldn't be recommended by Mozilla. This is a non-libre add-on to store and sync online passwords.
And the owning company is based in the USA. They will (or have) received request for user passwords like Lavabit did for their encrypted email.
https://en.wikipedia.org/wiki/LogMeIn

Libre/Open source software should be essential to recommend an add-on. They are using Mozilla's work without reciprocating.

And it violates Principle 4 and Principle 7 of Mozilla's manifesto https://www.mozilla.org/en-US/about/manifesto/

Great app, saves time and frustration.

Lastpass is a great program, if like me you have a head like a sieve for passwords, however my vault has become extremely untidy, with several duplicates for the same site and no indication of which is the currently used password. Also, when searching the vault, it does not find half the sites it has saved, for instance in the case of my yahoo email accounts, if I search for yahoo, only 1 out of the 5 accounts appear in search, however when it comes to logging, it does have them all available. Autologin is also hit and miss, some sites it will automatically log into, that is, do it with no interaction from me, with others it does not. Finally in terms of firefox, I have noticed that since I disabled Firefox from remembering my history, Lastpass will no longer automatically login into itself. Since I am the only user on my computer, this is my preferred option. Why it requires my search history in order to log into iteself automatically, I do not know, but it does make me quite suspicious. I will be exporting my passwords and looking into an alternative I think.

Works, but terrible memory leaks

It's not as easy to reclaim/make new master pasword as they suggest........

The extension neither sends my updated passwords back to the service to be synced with other devices, nor refreshes my passwords, even when I click on the extension icon, then click on refresh under advanced. I have to remove and re-add the addon in order to have my latest passwords if I ever change any. Please fix

enjoying a lot - cannot do without anymore - too old to remember so many passwords

This extension works smoothly and the app for Android works fantastic as well. Haven't had any issues beside a few sites not completely filling in (only username; Not the passwords) so I'm loving it.

Can't login (it says 'no internet connection available'). I've used lastpass on Android & Chrome and it's glitchy AF on those platforms, sad to see it's even worse on firefox. Time to give 1Password a whirl...

Everyday it gets worse and worse, PC or Android both is driving me nuts as it wont autofill properly. I'm seriously thinking about changing the application.

Нет ни русского, ни украинского языка!!! Буржуи думают только о деньгах!