Error messages that just say "there is an error on your form" but do not give any guidance as to what is wrong are a problem.For example, an error message like "date is incorrect" or "phone number is incorrect" do not provide formatting guidance.
Alert the user of any validation errors in an apparent and accessible manner.
Page Title (mention form errors)
Heading (mention form errors)
Provide informative feedback messages (what's wrong, how to fix it).
Allow the user to easily access the form elements that need to be modified.
link to elements in error
show only elements in error
Allow resubmission and revalidation of the form information. (Thanks to WebAIM)