Bad value “” for the attribute “xmlns” (only “http://www.w3.org/2000/svg” permitted here).

The xmlns attribute declares the XML namespace for an element. For SVG elements, the only permitted namespace is "http://www.w3.org/2000/svg". When this attribute is present but set to an empty string ("") or any value other than the correct namespace, the W3C validator reports an error because the browser cannot properly associate the element with the SVG specification.

In HTML5 documents (served as text/html), the xmlns attribute on <svg> is actually optional. The HTML parser automatically associates <svg> elements with the correct SVG namespace without needing an explicit declaration. However, if you do include the xmlns attribute — for example, because your SVG was exported from a design tool or copied from an XML-based source — it must contain the exact value "http://www.w3.org/2000/svg". An empty or incorrect value will cause a validation error and could lead to rendering issues in certain contexts.

This matters for several reasons:

• Standards compliance: The HTML specification explicitly restricts the allowed value for xmlns on SVG elements.
• Browser compatibility: While most modern browsers are forgiving in HTML mode, an incorrect namespace can cause problems when SVG content is used in XML contexts (such as XHTML or standalone .svg files).
• Interoperability: Tools and libraries that process your HTML may rely on the correct namespace to identify and manipulate SVG elements.

To fix this issue, you have two options:

1. Set the correct value: Replace the empty or incorrect xmlns value with "http://www.w3.org/2000/svg".
2. Remove the attribute entirely: Since xmlns is optional in HTML5, simply removing it is often the cleanest solution.

Examples

Incorrect: empty xmlns attribute

This triggers the validation error because the namespace value is an empty string:

<svg xmlns="" width="100" height="100">
  <circle cx="50" cy="50" r="40" fill="red" />
</svg>

Incorrect: wrong namespace value

Any value other than the correct SVG namespace will also trigger this error:

<svg xmlns="http://www.w3.org/2000/html" width="100" height="100">
  <circle cx="50" cy="50" r="40" fill="red" />
</svg>

Fix: use the correct namespace

Set xmlns to the only permitted value:

<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
  <circle cx="50" cy="50" r="40" fill="red" />
</svg>

Fix: remove the xmlns attribute

In an HTML5 document, you can omit xmlns altogether since the parser handles the namespace automatically:

<svg width="100" height="100">
  <circle cx="50" cy="50" r="40" fill="red" />
</svg>

Note on inline SVG from external sources

Design tools like Figma, Illustrator, or Inkscape often export SVG files with the xmlns attribute already set correctly. If you’re copying SVG markup and the xmlns value gets accidentally cleared or corrupted during the process, either restore it to "http://www.w3.org/2000/svg" or remove it before embedding the SVG in your HTML. Both approaches will produce valid, working markup.

Learn more:

MDN Reference

MDN Web Docs: SVG Namespace

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MDN Reference

MDN: SVG element

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