A “script” element with a “type” attribute whose value is neither a JavaScript MIME type, “module”, “importmap”, nor “speculationrules” (i.e., a data block) must not have a “src” attribute.

The src attribute is invalid on a <script> element whose type marks it as a data block, because the data lives in the element itself and there is nothing to fetch from elsewhere.

When the type attribute is anything other than a JavaScript MIME type, module, importmap, or speculationrules, the browser treats the element as a data block: inline content that other scripts on the page can read, but that is never downloaded or run. The most common example is application/ld+json structured data. The whole point of a data block is that it carries its content between the opening and closing tags, so pointing src at an external file makes no sense and is not allowed.

This usually happens when the type is set for a data block but the markup was copied from a real external script that still carries its src.

Examples

Invalid: src on a data block

<script type="application/ld+json" src="https://example.com/data.json"></script>

Valid: data block with inline content

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "Organization",
    "name": "Example"
  }
</script>

Remove the src attribute and place the data inline. If the file really is a script to load and run, fix the type value instead: use a JavaScript MIME type, module, or omit the attribute entirely.

Learn more:

MDN Reference

HTML script element - MDN

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MDN Reference

The script type attribute - MDN

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WHATWG Spec

Scripting - WHATWG HTML Standard

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