Why your hreflang tags are being ignored

Originally published on the WeLocale blog . Most SEO work is a matter of degree. You improve a title, you gain a little. hreflang is not like that. It either forms a valid set that search engines act on, or it does nothing at all, and the failure is completely silent. No warning, no penalty, no message in Search Console telling you the tags you carefully added are being discarded. We build a translation widget, which means we generate hreflang tags for other people's sites. This post is what we have learned about why they get ignored, including the parts where our own approach has real limits. The rule that breaks most setups hreflang is not a property of a page. It is a property of a set of pages, and every page in that set has to agree. If your English page says the German version is at /de/ , the German page has to say the English version is at / . If it does not, the declaration is one-way, and one-way declarations get dropped. Google calls these return links and treats their absence as a reason to distrust the whole set. This is why hreflang fails in a way that feels unfair. Every individual page looks correct when you inspect it. The problem only exists in the relationship between pages, which is exactly the thing you cannot see by viewing source on one URL. The corollary catches people too: each page must list itself . A German page whose tags mention English and French but not German is an incomplete set. Incomplete sets get dropped. The other four failure modes en-UK. The language code comes from ISO 639-1 and the region code from ISO 3166-1. In ISO 3166-1 the United Kingdom is GB. There is no UK. The tag is silently invalid, and it is easily the most common hreflang error on the web. Same class of mistake: lowercase regions, uppercase languages, and a region with no language at all. URLs that redirect. hreflang has to point at the final URL. If it points at http and you redirect to https, or it omits a trailing slash your server adds, the target is a redir