Error messages should be communicated based on the following two types of validation:
Inline Format Validation
Where a format requirement can be validated as the user enter their input i.e. the user enters a correctly formatted email address.
This is generally validated on form field exit (with some exceptions as the user is completing a field)
Data Validation on Submission
Where the data is validated i.e. the email address corresponds to an account in the system
Validated at a summary page level where any errors with the data are communicated back to the user and any validation-type errors are communicated to the user using the page-level error communication.
Support users in correcting the error via some or all the following methods:
Summarizing the errors at the top of the current page
- Linking directly inline to the field that has an error condition
- Where the user can find any required, external information i.e an account number on a printed statement