How do you inform users they have entered an invalid value in a field?

Creating an expression in the Validation field that displays an error message is the most effective method for informing users that they have entered an invalid value in a field. This approach ensures that the feedback is immediate and contextual, allowing the user to correct their input right away. The validation expression can be tailored to provide specific information about what was wrong with the input, guiding users toward entering valid data.

Using a validation expression not only communicates the error but can also prevent the submission of data until the user has addressed the issue. This reinforces data integrity and improves the user experience by providing real-time feedback.

Displaying a warning message, while useful, may not be as effective if it is separate from the validation field. A warning alone may not prevent users from submitting incorrect information. Making the field read-only would prevent any user interaction, which is not a solution for informing users about invalid inputs, and logging errors for administrator review does not provide immediate feedback to users, leaving them unaware of their input mistakes.