If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.
Provide suggestions for correcting input errors.
Assists users in completing forms and inputs without errors.
Not providing known suggestions for correcting errors. Remember to check these also with a screen reader! In many cases, a suggestion might be shown to a sighted user.
Fill in forms with test content - if you expect some type of content to fail, use that type of content to check for errors.