We have a long for which has 3 sections:
requester, shipping and billing
each section screen or more long so the form is 3+ screens long. From usability perspective what is the best way to display messages on the form.
Personally, I would like, at the top of the page before the form headers, to have something like:
There was an error with your form submission in the following section(s):
Shipping, Billing
Where Shipping and Billing are anchors that will take me down to that section of the form. Then, above that section, have the relevant messages to that section:
Shipping
- You need to fill in an address
[rest of form here]
Billing
- You need to fill in a name
[rest of form here]
I find it most usable if there is a generic error at the top of the form saying something like "There were errors submitting your information, please correct the fields in red" then show the more specific error messages next to each form field that had an error.
Grouped messages for each section at the top of the section
with a visual change to the form field which actually has the error.
Roger Hudson has a very good article on writing accessible forms and an example on error handling.
I like to have a dialogue that shows the type of effected fields, let's them click okay, then scrolls them to the first error in the form.
The affected field is then indicated with a flag/border/marker of some kind and a message letting them know the type of problem.
So, if they entered a malformed email address like "me@me'com" if would let them know the email address is malformed. The exact wording is really dependent on the type of user you are targeting.
I HATE forms that tell you there are errors at the top, then have tiny little asterisks by the fields.... ugh.
P.S. It also drives me nuts when a form has a "password" or other sensitive field and it gets emptied without marking it as a required, corrected field as well.