How can I make FF remember a password after I have inadvertently clicked "Never for this site"? The site is not listed in "exceptions".
There is no entry for the site in the "saved passwords" list. There is no entry at all in "exceptions".
Wšě wotmołwy (1)
You can remove all stored data from a specific domain via "Forget About This Site" in the right-click context menu of an history entry (Show All History or History sidebar).
Using "Forget About This Site" will remove everything from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious if you need to keep passwords or other data from that site. You can't recover from that "forget" unless you have a backup of the affected files.
It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.
The website may be using autocomplete=off to prevent Firefox from saving and filling the name and password.
You can remove autocomplete=off with a bookmarklet to make Firefox save the name and password.