Validation messages

Validation messages appear inline with form fields to help users correct input errors. They are the primary mechanism for communicating what went wrong and how to fix it.

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When to use

• On field blur (when the user leaves a field), not on every keystroke.
• On form submission when required fields are empty or invalid.
• Do not show validation errors before the user has interacted with a field.

Style

• Be specific: say what is wrong and how to fix it.
• Use plain language - do not expose technical error codes or internal validation rule names.
• Keep messages to one sentence.
• Do not use “Invalid” as a standalone message - explain why it is invalid.
• Do not blame the user. Use neutral, factual language.
• Do not use “Please” - omit it.

Do / Don’t

Do	Don’t
Enter a valid email address.	Invalid email.
Connection name is required.	Please fill out this field.
Password must be 8–32 characters.	Password does not meet requirements.
This name is already in use. Choose a different name.	Duplicate entry error.
Select at least one data domain.	You must make a selection.