XPath explained

Why XPath returns no results with a default namespace

In XPath 1.0, an unprefixed element name selects elements in no namespace. If your XML declares a default namespace, an expression such as /catalog/book will not select those namespaced elements.

XML Lens editorial · September 26, 2026

A small document that explains the problem

Consider a catalog from a supplier. The element names look familiar, but the default namespace gives catalog, book, and title a namespace URI. The id attribute remains unnamespaced.

<catalog xmlns="urn:example:books">
  <book id="b1">
    <title>Field Notes</title>
  </book>
</catalog>

<!-- XPath 1.0: no matching elements -->
/catalog/book/title

Use a prefix bound to the namespace URI

In an XPath tool that exposes namespace bindings, bind a query prefix such as b to urn:example:books, then qualify each element step. The query prefix is a label for the URI; it need not appear in the original document.

Namespace-binding controls differ by tool. In XML Lens, inspect a node’s namespace and generated XPath first rather than assuming a particular manually entered prefix has been registered.

# With b bound to urn:example:books
/b:catalog/b:book/b:title

# Filter on the unnamespaced id attribute
/b:catalog/b:book[@id="b1"]/b:title

An explicit expression without a prefix binding

For this example, match both the local name and the namespace URI. This is longer, but it makes the namespace requirement explicit without relying on a prefix configuration.

/*[local-name()="catalog" and namespace-uri()="urn:example:books"]
 /*[local-name()="book" and namespace-uri()="urn:example:books"]
 /*[local-name()="title" and namespace-uri()="urn:example:books"]

The expected result is one title element containing Field Notes.
Use the URI exactly as declared in the document.
Checking only local-name() can mix elements from different namespaces.

Debug one step at a time

Start at the root and add one path step at a time. If the first step matches and the next does not, inspect the next element’s name and namespace rather than changing the entire query.

Also check context: an absolute path begins at the document root, while a relative path starts from the current context node. A correct relative expression can return nothing when evaluated from the wrong place.

Save the working expression with a short note about its namespace assumptions. When a supplier changes its export format, that note helps you distinguish a data change from a query error.

Common questions

Should I remove xmlns to make the query work?

No. Removing a namespace changes the identity of the elements and may break validation or downstream processing. Adapt the query to the document.

Does a default namespace apply to an unprefixed attribute?

No. In the catalog example, id is unnamespaced even though book belongs to urn:example:books.

References

W3C XPath 1.0: node tests ↗W3C Namespaces in XML: namespace defaulting ↗

Try the workflow in XML Lens

Explore the relevant Mac workspaces and their capabilities.

← All XML guides