HTML Guide

Bad value X for attribute “datetime” on element “time”: The literal did not satisfy the time-datetime format.

The value used in the datetime attribute is not in a valid format.

The <time> HTML element represents a specific period in time. It may include the datetime attribute to translate dates into machine-readable format, allowing for better search engine results or custom features such as reminders.

Learn more:

MDN: time element

Related W3C validator issues

Attribute “required” is only allowed when the input type is “checkbox”, “date”, “datetime-local”, “email”, “file”, “month”, “number”, “password”, “radio”, “search”, “tel”, “text”, “time”, “url”, or “week”.

Bad value “datetime” for attribute “type” on element “input”.

type="datetime" is obsolete; it was removed from HTML and is not valid in modern browsers or validators.

Explanation

The input element’s type attribute accepts specific keywords defined by the HTML Living Standard. The keyword datetime was dropped; use either:

type="datetime-local" for a local date and time without timezone.
type="date" or type="time" when collecting them separately.
type="text" with a pattern or a JS widget when timezone-aware datetime is required.

Relevant attributes that still apply include name, value, min, max, and step (e.g., seconds for datetime-local).

HTML examples

Example reproducing the error

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Invalid input type</title>
</head>
<body>
  <form>
    <label>
      Meeting:
      <input type="datetime" name="meeting">
    </label>
  </form>
</body>
</html>

Valid fix with datetime-local

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Valid input type</title>
</head>
<body>
  <form>
    <label>
      Meeting:
      <input type="datetime-local" name="meeting" step="60">
    </label>
  </form>
</body>
</html>

The text content of element “time” was not in the required format: The literal did not satisfy the time-datetime format.

The <time> HTML element represents a specific period in time, which can be taken from the datetime attribute or from the text contents of the element.

In both cases, the time or datetime must be in a valid format, for example:

a valid year string

2011

a valid month string

2011-11

a valid date string

2011-11-18

a valid yearless date string

11-18

a valid week string

2011-W47

a valid time string

14:54

14:54:39

14:54:39.929

a valid local date and time string

2011-11-18T14:54:39.929

2011-11-18 14:54:39.929

a valid global date and time string

2011-11-18T14:54:39.929Z

2011-11-18T14:54:39.929-0400

2011-11-18T14:54:39.929-04:00

2011-11-18 14:54:39.929Z

2011-11-18 14:54:39.929-0400

2011-11-18 14:54:39.929-04:00

a valid duration string

PT4H18M3S

For example:

<p>
  The event will take place on <time datetime="2025-03-20T13:00">March 20, 2025</time>.
</p>