I'm encountering the bug described at "Login form error message is redundant and does not make sense". In short, if a user enters invalid credentials once, an inline error message appears on the user login page. When the user enters valid credentials and successfully logs in, the user sees an error message at the top of the screen (e.g., "1 error has been found: username"), but that is no longer correct.
According to this blog post one can disable inline form errors for a particular form by adding
$form['#disable_inline_form_errors'] = TRUE; to the form definition, and I have seen that code snippet elsewhere, too. But I can't find any instructions for implementing it. Does anyone have an example?