Does it still happen with all your extensions disabled?

Thanks for replying. The answer is yes.

However, I had enough of it and tried again with a brand new Firefox profile. This time, the login is retained. I now have to locate which setting or about:config change caused the problem.

Will post back if I find anything conclusive.

Forgot to mention that this seemed to be a Facebook-only issue. Other logins were normally retained, including Google.

i currently have this issue and it took me awhile to find someone else with the same problem. i strongly believe this happened as a result of copying my firefox profile from another PC since my logon was retained on that PC prior to copying my firefox profile to another PC, now this problem exists on both PC's. this is likely a security measure employed by facebook, possibly using a hardware hash from the PC its first set on. i would prefer not having to create a new profile to solve this issue so i will figure out another way to solve it and post back here with a found solution. edit: to solve this problem, go to firefox settings > privacy and security > manage data, type in "facebook" and clear all the stored data. facebook stays logged in now.

You can use these steps to make a website recognize and remember you.

• create a cookie allow exception with the proper protocol (https:// or http://) to make a website remember you

You can check that you aren't clearing important cookies.

• using "Delete cookies and site data when Firefox is closed" to clear cookies keeps cookies with an allow exception
  in 102+ version toggling this setting makes changes to the "Clear history when Firefox closes" settings and those settings prevail
• using "Clear history when Firefox closes" in Firefox 102+ honors exceptions and keeps cookies with an allow exception, previous versions removed all cookies

Make sure to keep the "Site settings".

• clearing "Site settings" clears exceptions for cookies, images, pop-up windows, and software installation and exceptions for passwords and other website specific data

• Settings -> Privacy & Security
  Cookies and Site Data: "Manage Exceptions"
• Settings -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings

If clearing cookies doesn't help, it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and when present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

I believe this is also related to the "storage" folder in the profile, which holds website information too. Try this:

Clear all cookies, cache, history etc. Close Firefox Delete the aforementioned cookies.sqlite files Delete everything in the storage folder, except for the moz-extension+++ files. These hold the settings for each extension. Start FF Log in to FB again, and check if the login is remembered the next time you start FF.

Clearing the storage/defaults folder (indexedDB) like you posted sounds to me like overkill in most cases as this removes data for all websites stored in local storage. You can first use "Forget About This Site" in the right-click context menu of a Facebook.com history item to cleanup cookies and history and other Facebook data and combine that with removing cookies.sqlite.

It might be overkill, but it was the only way that solved the issue on one time it reoccurred. I guess one might try to only delete the Facebook-related folder in there. Should be easy to identify, I currently see this folder inside storage/default:

https+++www.facebook.com^userContextId=6

Make sure Firefox is not running!

I'll also add this info: I have 2FA enabled on Facebook. On all the occasions I kept logging in and Firefox did NOT remember the login, Facebook would not ask me for a 2FA code. It did throw the usual warnings "is this you?", "remember browser?" etc.

When I also deleted the aforementioned data inside the storage folder, only then did Facebook ask for the 2FA code again and this time, the login was remembered.

Note that userContextId not equal to zero means to this is about storage used for a specific container, see containers.json in the Firefox profile folder to see what container this is about.

Now i have same issue. I deleted cookies.sqlite and it helped, but now issue came back. Is there any solutions which can help? This only happens on facebook and Firefox. Example instagram, twitter.. reddit.. no any issues. Also any issues on chrome or any other browser..

I doubt its any of my extesions what im using. I will not reinstall browser because it not helped last time and it brings same settings somehow when i want delete fully.