Hreflang tags are present and structurally valid for multilingual sites

Multilingual sites without hreflang tags serve the wrong language to the wrong audience: French users see the English page in search results, bounce rates spike, and Google interprets the engagement signal as a quality problem. Missing x-default means Google has no fallback for locales outside your declared set, so international queries return nothing. Relative URLs in hreflang are ignored entirely by crawlers.

In generateMetadata, set alternates.languages with an entry per supported locale plus an x-default pointing to your primary language. Use absolute HTTPS URLs and valid BCP-47 codes (en, fr-CA, not english). Verify the set is bidirectional — every localized page must reference every other locale.

// app/[locale]/layout.tsx
export const metadata = { alternates: { languages: { en: 'https://yoursite.com/en', fr: 'https://yoursite.com/fr', 'x-default': 'https://yoursite.com' } } }