As per "UX guidelines" what should be the error message for a dimmpley Login for having 2 basic fields "Username" & Password.

So if a User Enter a username with "Space or special characters[,/<>{}]", should the message be very general saying "Invalid Username" or "Please enter a valid username"? or should it be more specific by telling them the special charaters they have added are not acceptable for this filed?

Here is what I am doing right now!

enter image description here

Please suggest!


4 Answers 4


If your page clearly states what character are and are not valid when registering, then a generic message such as "Invalid Username" is just fine.

If not, then it would definitely be helpful to show the username guidelines when you give the error. Another option that you have is when the user is actually typing in a username, you could have a tooltip that pops up with the username guidelines (gmail does this). This way you could maintain a minimal design and keep the page aesthetically pleasing, while also giving important and relevant information.

I don't think it's ever necessary to specifically SHOW which characters that the user has used are invalid. That's a lot of extra code for something that doesn't add much value to the experience.

Attached are ways Amazon and GMail handle username error checking enter image description here

enter image description here enter image description here

  • Thanks for sharing the examples... Really appreciate it!!! I have also updated my question with my screenshot... n I think the generic message looks fine... what do you think?
    – AT - UID
    Commented Jun 2, 2014 at 19:31
  • 2
    Do you have the rules for a valid username elsewhere on the page? Like see with google, while you're typing it says "You can use letters numbers, and periods." And on the error screen it says "Please use only letters (a-z), numbers, and periods." Right now I don't see where the rules are to what DOES make a valid username on your screenshot. How am I, a user, supposed to know what is valid and what is not? Commented Jun 2, 2014 at 19:40
  • @AnindyaBasu hits the nail on the head above. 'Valid' and 'Invalid' are ambiguous and potentially scary words. Just tell the user what needs to go into the box.
    – Max
    Commented Jun 2, 2014 at 19:51
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    I agree with "If your page clearly states..." — I, too often, run into my email-as-username being rejected for unknown reasons with no explanation. Is it because I used a + in my email [email protected] or is it because my .us domain is not 3 or more characters? Both are bad reasons to reject my completely valid, working, and real email address, but without feedback on what you think is wrong, I have little chance to "correct" it. Tell me what part you think is invalid. <rant>"strange" email addresses are more valid than you think they are </rant>
    – Stephen P
    Commented Jun 5, 2014 at 0:51

Do as gmail does it.Instead of invalid username that does not answer the query completely, include a custom message in the tooltip asking your users to do as directed in case your label field value is somewhat complicated.


What is a valid user name? Is it a user name that was sent to the user from the application when he or she signed up? if so, you should indicate it instead of a generic "Please enter a valid username."

If the user name is what the user entered when signing up, you should have a link "forgot my user name."

Users are forgetful, and instead of making them try again and again you should make it easier for them to restore that user name and let them start working with your application.

Mailchimp.com is a great example of how to create a proper log-in page.

  • OP is specifically asking about Error message and how to handle them. Your answer does not address OP's question. Commented Aug 7, 2014 at 20:34

I've actually found it a lot easier when websites i don't use frequently tell me "There is no account matching that username" when i give an incorrect username/email address

For example wix.com present a lovely little pop-up that says "This email address doesn’t match any account. Double check and try again."

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