Bad value X for attribute “method” on element “form”.

The method attribute on <form> accepts only get, post or dialog, so an empty value or an HTTP verb like PUT or DELETE is invalid.

The keywords are case-insensitive, so POST and post both work, but the value must match one of the three exactly. Extra whitespace, as in method=" post", also triggers this error. dialog only makes sense for a form inside a <dialog> element, where submitting closes the dialog instead of sending a request.

Browsers fall back to GET when the value is invalid. An empty method="" often comes from a template that prints an unset variable. The form still submits as GET, so remove the attribute or write method="get". An unsupported verb causes a real bug: a form with method="PUT" or method="DELETE" sends a GET request with the field values in the URL, so the server's PUT or DELETE handler never runs.

HTML forms can't send PUT, PATCH or DELETE requests. Use method="post" and tell the server which verb you meant. Frameworks such as Rails, Laravel and Phoenix read a hidden _method field for this, or you can send the request with fetch() from JavaScript.

Empty value

Invalid example

<form action="/search" method="">
  <label for="q">Search</label>
  <input id="q" name="q" type="search">
  <button>Search</button>
</form>

Valid example

<form action="/search" method="get">
  <label for="q">Search</label>
  <input id="q" name="q" type="search">
  <button>Search</button>
</form>

Unsupported HTTP verb

Invalid example

<form action="/profile" method="PUT">
  <label for="name">Name</label>
  <input id="name" name="name">
  <button>Save</button>
</form>

Valid example

<form action="/profile" method="post">
  <input type="hidden" name="_method" value="put">
  <label for="name">Name</label>
  <input id="name" name="name">
  <button>Save</button>
</form>

Learn more:

MDN Reference

MDN Web Docs: The form element

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MDN Reference

MDN Web Docs: HTMLFormElement.method

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