Error Messages Design: Best Practices

Error messages should be simple and direct, preferably actionable, written in an easy-to – read language and quick to understand.

Avoid obscure codes and abbreviations like “the success of the received response is false.”

Provide succinct, straightforward explanations of the issue, rather than “an error has been made.”
Stop accusing people or asking them to do something wrong — saying it was a “illegal command” for example.
Provide constructive error messages in context, so that people can solve the problem.
Avoid only turning the field red to signify an mistake. It’s not making it accessible to disabled people. Having other visual signs which the colorblind can see is often best.
For input fields on the forms, use inline validation.
Error notices do not go away until people fix the problem.

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