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Understanding SC 3.3.3:Error Suggestion (Level AA)

In Brief

Users get suggestions on how to resolve errors.
What to do
Where errors are detected, suggest known ways to correct them.
Why it's important
People can address errors faster and with reduced effort.


The intent of this Success Criterion is to ensure that users receive appropriate suggestions for correction of an input error if it is possible. The definition of "input error" says that it is "information provided by the user that is not accepted" by the system. Some examples of information that is not accepted include information that is required but omitted by the user and information that is provided by the user but that falls outside the required data format or allowed values.

Success Criterion 3.3.1 provides for notification of errors. However, persons with cognitive limitations may find it difficult to understand how to correct the errors. People with visual disabilities may not be able to figure out exactly how to correct the error. In the case of an unsuccessful form submission, users may abandon the form because they may be unsure of how to correct the error even though they are aware that it has occurred.

The content author may provide the description of the error, or the user agent may provide the description of the error based on technology-specific, programmatically determined information.


  • Providing information about how to correct input errors allows users who have learning disabilities to fill in a form successfully.
  • Users who are blind or have impaired vision understand more easily the nature of the input error and how to correct it.
  • People with motion impairment can reduce the number of times they need to change an input value.


Additional Help for Correcting An Input Error
The result of a form that was not successfully submitted describes an input error in place in the page along with the correct input and offers additional help for the form field that caused the input error.
Suggestions from a Limited Set of Values

An input field requires that a month name be entered. If the user enters "12," suggestions for correction may include:

  • A list of the acceptable values, e.g., "Choose one of: January, February, March, April, May, June, July, August, September, October, November, December."
  • The conversion of the input data interpreted as a different month format, e.g., "Do you mean 'December'?"


Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.


In some cases, more than one of these situations may apply. For example, when a mandatory field also requires the data to be in a specific format.

Sufficient Techniques

Select the situation below that matches your content. Each situation includes techniques or combinations of techniques that are known and documented to be sufficient for that situation.

Situation A: If information for a field is required to be in a specific data format:

Situation B: Information provided by the user is required to be one of a limited set of values:

Advisory Techniques

Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.

Client-Side Scripting Techniques (Advisory)

Key Terms

assistive technology

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents


Functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).


Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.


The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.

input error

information provided by the user that is not accepted


This includes:

  1. Information that is required by the Web page but omitted by the user
  2. Information that is provided by the user but that falls outside the required data format or values
user agent

any software that retrieves and presents Web content for users

web page

a non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent


Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.


For the purposes of conformance with these guidelines, a resource must be "non-embedded" within the scope of conformance to be considered a Web page.

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