I discovered last night that if you try to log in to facebook with an email address that is similar to one that has already logged on that computer, it will autocorrect your login information and try to log you in as the previous login. Even if you click the "Not {Username}?" button and reenter the information, it still won't let you log in as the second user.

From a user experience standpoint, it was rather irritating. Is there a reason for this that I am just not seeing?

Just to clarify, it was Facebook changing it AFTER I hit the submit button, not my web browser autofilling it. It even displayed a message saying that there was a "slight typo" or something like that in my information.

  • it is not sounding like a feature or anything. on the other hand, it sounds like the browser cookies from the previous login are somehow corrupted. can u plz add some more contextual information? Or retry after clearing the cookies from browser-settings.
    – kmonsoor
    Nov 9, 2013 at 22:48

4 Answers 4


Interesting - I hadn't noticed that feature before. With Facebook's implementation you do at least still have to re-enter the password before being able to access the account. It is, I suppose, handy if you really have just mistyped your email address. I can understand that it would be annoying if you had multiple Facebook accounts with very similar email addresses but Facebook would probably argue that you shouldn't have multiple accounts and the chances of two strangers with such similar email addresses using the same machine in quick succession is very unlikely. I wonder if the feature came as a result of behaviour Facebook observed in their logs.

  • 2
    I found this out when my wife, who has a similar email address to mine, wanted to check something on her facebook account from my laptop.
    – Kevin
    Sep 21, 2012 at 14:55
  • @Kevin I see. I assume the "Not {Username}?" feature it meant to handle that. Buggy perhaps.
    – Matt Obee
    Sep 21, 2012 at 15:00

With Facebook supporting something like 600 million users it's difficult to believe they could handle customer support for all their log in issues. Since they provide multiple levels of security, including remembering what devices you access from, it's likely this method was added to reduce support overhead.

Rather then have a person support the user who fails to log in, they are trying to automate the process. People who fail to log in or forget their email they used represent a very small percentage. So small that I think most websites wouldn't benefit from something like this, but with Facebook even a percentage of a percentage is still thousands of users.

  • 1
    That makes sense, but you'd think that they could do something, like "NO, that isn't me and I didn't make a typo, please use what I typed and stop changing it."
    – Kevin
    Sep 21, 2012 at 15:50
  • 2
    I went and gave this a try and it's kind of creepy that it corrected my email address. It feels less secure this way. It's not something I'd want to add to my websites.
    – Reactgular
    Sep 21, 2012 at 16:16

I haven't checked, but I assume (/hope) that they're only doing it if you're trying to log in from the same IP as last time - or even only if it's the IP you usually log in from.

In that case I think there is sense in this approach and it does help the user, it's basically the same autocorrect you get in Word or other apps. Basically, it's a good idea when the app has good reason to believe that it's the right person who has just made a typo. In other cases it's both annoying and a major security flaw.


Yes and No

Yes,Because it is making it easier for the user to realize that he has perhaps made a mistake and is reducing a potential step for him not requiring him to enter his email id. I also like the fact that they do ask you for the password even though you might have entered the right password

No, Because it opens up potential security holes by displaying email ids and even user profiles( my profile is not searchable on the web and cant be found by people on facebook unless they are friends of friends). But when I tried this, I noticed that a user could easily see that I was on facebook (assuming he tried an email id close to mine.Another potential bug I found while trying this out was that it automatically assumed that the user was me even when I entered a wrong password

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