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SEO026 · hreflang validity

Severity: warning

What it checks

Section titled “What it checks”

Validates <link rel="alternate" hreflang="…"> alternates. The rule is opt-in: a page with no hreflang alternates is never flagged. When alternates exist it flags:

  • a malformed hreflang value (not x-default or a well-formed BCP-47 code such as en, en-US, zh-Hant, or es-419), and
  • a set of two or more alternates with no x-default.

Why it matters

Section titled “Why it matters”

A malformed hreflang code or a missing x-default breaks international targeting, so search engines may serve the wrong language version or ignore the annotations.

How to fix

Section titled “How to fix”
<svelte:head>
  <link rel="alternate" hreflang="en" href="https://example.com/en/" />
  <link rel="alternate" hreflang="de" href="https://example.com/de/" />
  <link rel="alternate" hreflang="x-default" href="https://example.com/" />
</svelte:head>