I am trying to determine what would be the most effective method of notifying a user that some of the fields they have filled out on the online form is invalid or required.

The form itself is to enter data for readings taken off machinery, so accuracy is an important factor.

My gut is telling me that in-page messages are more effective as the user wont have to recall what they are required to fill in or change once the error window is shut.

Have not been able to find any real research on this online, so throwing it to the floor for some answers.

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  • 1
    I wouldn't call your 'inline' option truly inline actually. To be inline you'd need to have the individual error messages against the fields themselves as well as displayed at the top.
    – JonW
    Commented Jan 27, 2015 at 16:38
  • Duly noted, my bad - have edited my question
    – IronBasset
    Commented Jan 27, 2015 at 16:41
  • 2
    Ah well in that case i would suggest considering actual Inline errors rather than these two options. You can find useful info on this very related (possible duplicate) question: ux.stackexchange.com/questions/26173/…
    – JonW
    Commented Jan 27, 2015 at 16:44

4 Answers 4


Pop up errors Drawbacks:

  • The pop-up goes away in order to correct the form => I have to remember the errors.
  • Their just plain data, "unlinked" with the particular error source => I have to locate the source of the errors if I can remember them. (unless you also want to color the input or showing some other clue, but I will harder anyway compared with actual inline errors)
  • If I get an error after editing, I will have again to remember an relocate the error source.

Up to this point, users are yelling: "Don't make me think!"

  • They are unnecessary invasive. I don't want the pop-up itself to prevent me to at least check the errors of the form before closing the pop-up. For a critical decision as deleting some record or confirming an important action, pop-ups could be a valid option, but I don't see their advantage on error message displaying.

I think no research is needed for this as the usability differences are huge.
As JonW mention in his comments, I also recommend to go with actual inline error messages. Also try to complement it with some error-prevention design.

There's plenty information about form design including error messages, both in this site and in other UX-related ones.


As per your edit, I am assuming InPage rather than InLine.

I think it depends on the length of your form. I have seen many times where Users have to click the Submit button way down at the bottom, the In Page validation kicks in but Users are not scrolled back up to the inpage validation message. So they have no idea why the form is not submitting! Either you should scroll them up or have an alert.

Another factor is Response Time. If you measure that the round trip from the server is taking a long time, the user may become distracted and not notice the in page validation when it shows. A popup always grabs user attention.

A few suggestions:

  1. You could also have a combination of Popup to alert the user, thus negating the above 2 points and then keep the validation message in page to take care of your point regarding recall.

  2. Have Inline validation next to each input box and show the message there. This does seem to be the modern way of going about it.


Like other people said, inline errors is more user friendly. To add to this, pop-ups should be used (if anything) on finished tasks, success messages, etc, but user has to be able to see what errors has he/she made in order to make the appropriate corrections. And for this, you need some kind of inline display.

Now, in this scenario (and based on your screen capture as well), the most common way to display these errors is ON SUBMIT, which is correct, but can be enhanced by using AJAX requests, so errors can be corrected immediately as soon as the form is being filled.

This way, your users won't have to submit the form, you'll be able to tell them EXACTLY how you want the data to be provided and you won't have "faux submission" that mess your statistics.

The data formatting problem is specially true with password fields since you'll need to enter (and re-enter) passwords every time the page loads, and this is a very common UX error. You'll also see this issue on date (when using text fields), credit card numbers, etc. And it's as simple to solve as to perform an asynchronous request and some validation before submitting anything. Furthermore, you can "mute" the submit button until validation is successfully performed


There is a third possibility, which is do both! Have a pop-up that has the missing/invalid fields fillable. You might want to fall back to inPage errors if there are more than 2-3 invalid fields, or only present the user with 2-3 fields at a time. If there are only a couple of invalid items and you have a long form just showing the missing information AND making it fillable from the pop-up message can be a huge savings if it is a long form.

However this might NOT be a good fit if context is important to individual questions. If the missing information relies on previous answers taking it out of context might make it harder (or impossible) to answer.

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