Error messages and validation

Error messages name the problem and show how and where to fix it.

Every field needs a unique error message.

For radio buttons, write “Choose [form field name].”, like “Choose yes or no.”

For text entry, write “Enter [form field name].”, like “Enter your name.”

Wait to validate. Only show error messages after a user has exited the field.

More: Writing clearer error messages

Validation

If an answer makes a user ineligible for a program or is not accepted, the form should:

1. Stop them from filling out the rest of the form

2. Explain why they cannot proceed

3. Give them another place to go

For example, a user may need to be more than 18 to register for a service. Their date of birth makes them ineligible. After they input their DOB, the error message reads:

CityTestSF cannot accept people who are under 18 years old. Call a doctor to find another way to get tested.