An empty string is not a valid value for the autocomplete attribute on an input element.
The autocomplete attribute controls whether the browser can autofill input values, and it requires a valid, non-empty value according to the HTML specification. Acceptable values are on, off, or specific autocomplete tokens such as name, email, username, etc. Leaving it empty, like autocomplete="", causes validation errors.
Incorrect example:
<input type="text" name="username" autocomplete="">
Correct examples:
Enable browser autocomplete:
<input type="text" name="username" autocomplete="on">
Disable browser autocomplete:
<input type="text" name="username" autocomplete="off">
Use a specific token (recommended for forms that collect particular data):
<input type="email" name="useremail" autocomplete="email">