I tried that before and did it again:
"Alles" means everything in the cache. But the result is still the same.
I give up. I have a ticket and hope LastPass will find a solution in the software. For the moment I know how to find my passwords with the help of my phone. But thank you for your suggestions to help me.
Our development team has released an update for the LastPass browser extensions today that should resolve the issues with logging in to FireFox as discussed in this thread.
Please look out for the v4.57.1 update to be released later today here: https://lastpass.com/download
Also having trouble with login. Before "add-on" would open a web URL, then I would select Log-in and it would work. Now it takes me to more of an app "pop=up" that will not accept the exact same credentials.
I've been having the same issue for at least a month, every couple of days when I login using the extension, I get a bigger login block and it's always denied.
MacOS Catalina 10.15.6,Firefox 81.0, LastPass Extension - latest, reinstalled today. I always run Firefox as private windows, do not remember history. This issue started a month or so ago.
I can close Firefox, reopen, and and after a couple of times, I get the "normal" recent web URL page, select login and it works ok, until next time. (BTW, after years, why do I suddenly need to see a Web URL page when the extension is much less intrusive?).
I have just checked and the updated extension is now on both Edge and Chrome, but Firefox is still using the old extension version and the website download page is still showing the 126.96.36.199 version.
I have uninstalled and reinstalled the extension - still same version.
Have changed extension settings to automatically update.
I have had to turn off the setting that I prefer - "Forget history" - in order to get operability.
If I turn on "Forget history" or manually delete history I go back to the unknown error issue.
Thanks to the team for updating the other two browsers, will wait with anticipation for the update to roll out to Firefox.
I also can not log in using Lastpass Firefox extension in Firefox 81.0 (64 bit).
I get a large log in window and error message as described by others.