hreflang disagrees with html lang: fix contradictory signals
When a page's self hreflang code disagrees with its html lang attribute, Google gets contradictory language signals and may distrust the whole hreflang cluster. Find mismatches free and align both to one BCP-47 code.
What it means
The page's self-referencing hreflang entry declares one language, but the <html lang=""> attribute declares a different one — for example hreflang="fr-FR" alongside <html lang="en">. The two give search engines contradictory information about the page's language in a single response.
Why it matters
Google uses both signals to determine a page's language: the hreflang annotation for the language/region it serves and its alternates, and the html lang attribute for the language the document is written in. Google may use html lang as a validation input when processing hreflang clusters, so a conflict can make it distrust the entire annotation for that URL or misassign the page to the wrong language cluster — routing the wrong audience to the page, or failing to route the intended one. The mismatch usually arises when hreflang (in a sitemap, plugin or header) and the theme's html lang are managed by different systems and one is updated in isolation, or when the two use different code formats (en_US vs en-US).
How to fix it
- Inspect both values on the page:
curl -s URL | grep -E '(html lang|hreflang)'. - Decide the correct language for the page's actual content.
- Align both to the same BCP-47 code — set
<html lang="fr-FR">and the selfhreflang="fr-FR"to match. - If hreflang is in an XML sitemap, update that URL's entry too; then resubmit the sitemap and monitor the International Targeting report.
When it's not a problem
A partial mismatch where the language agrees but only the region differs (html lang="en" vs hreflang="en-US") is far less severe and often harmless — Crawlinx compares only the primary language subtag, so this case is not flagged. If the page has no hreflang annotations, the rule does not apply.
How common is it?
96 audited sites in our corpus currently show this issue. The breakdowns below show which platforms, gatekeepers, verticals and countries are most exposed.
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