Hreflang uses invalid language code: what it is, why it matters, and how to fix it

One or more hreflang annotations use an invalid ISO 639-1 language code or ISO 3166-1 Alpha-2 country code. Google will ignore hreflang entries with unrecognized codes.

Invalid language codes cause Google to silently ignore the hreflang annotation, meaning your international targeting will not work for the affected language/region. Common mistakes include using 'uk' for Ukrainian (should be 'uk' for country code but 'uk' is also valid as language), or using three-letter codes instead of two-letter codes.

Verify that all hreflang language codes use valid ISO 639-1 two-letter language codes and optionally ISO 3166-1 Alpha-2 country codes. Use format like 'en', 'en-US', 'fr-CA'. Use Google's documentation as a reference for valid codes.

This is a medium-severity issue: individually modest, but it compounds — dozens of medium issues across hundreds of pages add up to a real quality deficit in how search engines assess the site. It belongs to the indexability family of checks.

Run a free Dr Urls audit: it crawls your site, detects hreflang uses invalid language code on every affected page, shows example URLs, and generates a ready-to-use fix task. Re-scan after fixing to verify the issue is gone.