Bad value X for attribute “value” on element “input”: The literal did not satisfy the date format.

The value of an <input type="date"> must be a full date written as YYYY-MM-DD, so keywords like today and localized dates like 15/03/2025 are rejected.

HTML has no relative date keywords. A date input's value has to be a valid date string: a four-digit year, a two-digit month and a two-digit day, joined by hyphens, as in 2025-03-15. Months and days need their leading zero (2025-3-5 fails), and the value can't include a time, because 2025-03-15T10:00 belongs to type="datetime-local". The min and max attributes of a date input follow the same format. An empty value is allowed and leaves the field blank.

Browsers discard a value they can't parse, so the field shows up empty instead of showing the date you meant. The date picker displays the date in the user's own locale, but the markup always uses YYYY-MM-DD, whatever language the page is written in.

To prefill today's date, write the actual date into value when the server renders the page. On a static page, leave value out and set it from a script after the page loads.

Invalid example

<label for="start">Start date</label>
<input type="date" id="start" name="start" value="today">

Valid example

<label for="start">Start date</label>
<input type="date" id="start" name="start" value="2025-03-15">

Setting today's date with JavaScript

<label for="end">End date</label>
<input type="date" id="end" name="end">
<script>
  const now = new Date();
  const month = String(now.getMonth() + 1).padStart(2, "0");
  const day = String(now.getDate()).padStart(2, "0");
  document.getElementById("end").value = now.getFullYear() + "-" + month + "-" + day;
</script>

Learn more:

MDN Reference

MDN: <input type="date">

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MDN Reference

MDN: Date and time formats used in HTML

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