Success Criterion 3.3.1: Error Identification

Understanding Success Criterion: 

If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

Accessibility Level: 
Intent of Success Criterion: 

The intent of this Success Criterion is to ensure that users are aware that an error has occurred and can determine what is wrong. The error message should be as specific as possible. In the case of an unsuccessful form submission, re-displaying the form and indicating the fields in error is insufficient for some users to perceive that an error has occurred. Screen reader users, for example, will not know there was an error until they encounter one of the indicators. They may abandon the form altogether before encountering the error indicator, thinking that the page simply is not functional. Per the definition in WCAG 2.0, an "input error" is information provided by the user that is not accepted. This includes:

  • information that is required by the web page but omitted by the user, or
  • information that is provided by the user but that falls outside the required data format or allowed values.

For example:

  • the user fails to enter the proper abbreviation in to state, province, region, etc. field;
  • the user enters a state abbreviation that is not a valid state;
  • the user enters a non existent zip or postal code;
  • the user enters a birth date 2 years in the future;
  • the user enters alphabetic characters or parentheses into their phone number field that only accepts numbers;
  • the user enters a bid that is below the previous bid or the minimum bid increment.

Note: If a user enters a value that is too high or too low, and the coding on the page automatically changes that value to fall within the allowed range, the user's error would still need to be described to them as required by the success criterion. Such an error description telling the person of the changed value would meet both this success criterion (Error Identification) and Success Criterion 3.3.3 (Error Suggestion).
The identification and description of an error can be combined with programmatic information that user agents or assistive technologies can use to identify an error and provide error information to the user. For example, certain technologies can specify that the user's input must not fall outside a specific range, or that a form field is required. Currently, few technologies support this kind of programmatic information, but the Success Criterion does not require, nor prevent it.
It is perfectly acceptable to indicate the error in other ways such as image, color etc, in addition to the text description.
See also Understanding Success Criterion 3.3.3 Error Suggestion.

Specific Benefits of Success Criterion: 
  • Providing information about input errors in text allows users who are blind or colorblind to perceive the fact that an error occurred.
  • This Success Criterion may help people with cognitive, language, and learning disabilities who have difficulty understanding the meaning represented by icons and other visual cues.