tools -> options -> security -> remember passwords for sites [make sure it is ticked]

I already have that selected. As I said in my question, most passwords are saved.

Can you post a link to a publicly accessible page (i.e. no authentication or signing on required)?

A detail like a website remembering you (log you in automatically) is stored in a cookie.

You can use these steps to make a website remember you:

• Create a cookie 'allow' exception to keep such cookies, especially in case of secure websites and when cookies expire when you close Firefox.
• Tools > Options > Privacy > "Use custom settings for history" > Cookies: Exceptions

In case you use "Clear history when Firefox closes" or otherwise clear history.

• do not clear the Cookies
• do not clear the Site Preferences

• Tools > Options > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" > Settings
• https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history

Clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, passwords, and other website specific data.

Clearing cookies will remove all specified (selected) cookies including cookies with an allow exception that you would like to keep.

Here's a link to a publicly accessible site with no login:

http://www.bbc.co.uk/

Cookies and Site Preferences aren't checked to be cleared. I've only just enabled clearing history on exit so that wasn't related to this problem, which has been going on for a few weeks at least. To make sure that isn't the problem I've disabled clearing history on exit again.

As you suggested, I've made cookie "allow" exceptions for a site that doesn't remember the login.

Am I correct that this is about the website remembering you and not about storing the name and password in the Password Manager?

Did you verify that you keep the cookies?

Make sure that you do not run Firefox in permanent Private Browsing mode (Never remember history).

• https://support.mozilla.org/kb/Private+Browsing

• Tools > Options > Privacy > Firefox will: "Use custom settings for history"
• Deselect: [ ] "Always use Private Browsing mode"

Possibly also check for other cookie issues:

• http://kb.mozillazine.org/Websites_report_cookies_are_disabled
• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies

The problem is Password Manager not saving the login details. That is the prompt that comes up when the site requests login data. It offers to save it but doesn't. Password Manager used to save the data and it saves data for other sites (a new entry was created for this forum today).

Yes I keep cookies.

No, I never use Private Browsing and it isn't checked under that option.

You can check for the presence of multiple, uppercase/lowercase, versions of this name and password and for entries with an empty name.

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious and if you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of the involved 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.

It is possible that there is a problem with the key3.db file (encryption key) and the logins.json file (encrypted names and passwords) in Firefox.

You can rename the key3.db file (key3.db.old) and logins.json file (logins.json.old) and rename a possible signons.sqlite file (signons.sqlite.old) or move them to another folder to make it possible to undo the action. You need to set a new Master Password after renaming or deleting key3.db and all currently saved passwords are lost. If that has worked then you can remove the renamed files that are no longer needed. Otherwise you can rename the files to their previous names (key3.db and logins.json).

If you see passwords in the Password Manager (Tools > Options > Security: Passwords > "Saved Passwords") then you can save the existing passwords with the Password Exporter extension before removing/renaming files and re-import them afterward.

• Password Exporter: https://addons.mozilla.org/firefox/addon/password-exporter/

Check that the exported (xml) file has all the names and passwords.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

I'm no longer sure this is just a Firefox problem. I tried accessing the site from Chrome and it doesn't even offer to save a password, nor does it remember it.

Creating "allow" exceptions didn't make any difference. I'll try "forget about site" and see if that resets anything.

See also:

• Saved Password Editor: https://addons.mozilla.org/firefox/addon/saved-password-editor/

The saved password editor allowed me to create a new entry for the site in Password Manager. It turns out it's the annotated type and maybe the current Firefox version has trouble creating an entry like that. whatever the reason this addon solves the problem. Thanks for identifying the solution.