This check fires when hreflang exists but is built wrong: invalid language or region codes, tags in the wrong place, or two delivery methods fighting each other. The markup is present, so it looks handled, but Google either can't parse it or gets contradictory instructions and drops the lot.
What this check flags and why it bites
Misconfigured hreflang is worse than none, because it burns crawl budget and gives you a false sense that international targeting is solved. Common culprits: a made-up code like en-uk (the country is gb), a region code with no language, hreflang <link> tags dumped in the <body> instead of the <head>, or the same URLs annotated in both HTML and the XML sitemap with different values. Any of these can void the cluster.
Wrong vs right, side by side
Here is a block riddled with the classic mistakes, followed by its corrected form:
<!-- BROKEN -->
<link rel="alternate" hreflang="en-uk" href="/uk/" /> <!-- invalid country code -->
<link rel="alternate" hreflang="gb" href="/gb-page/" /> <!-- region with no language -->
<link rel="alternate" hreflang="fr_FR" href="/fr/" /> <!-- underscore, must be hyphen -->
<link rel="alternate" hreflang="us" href="/us/" /> <!-- "us" is not a language -->
<!-- FIXED -->
<link rel="alternate" hreflang="en-gb" href="https://example.com/uk/" />
<link rel="alternate" hreflang="en-us" href="https://example.com/us/" />
<link rel="alternate" hreflang="fr-fr" href="https://example.com/fr/" />
<link rel="alternate" hreflang="x-default" href="https://example.com/" />The fixes: hyphens not underscores, real ISO 639-1 language codes, ISO 3166-1 Alpha-2 country codes, absolute URLs, and a language always present before any region.
The configuration errors that trip sites
| Misconfiguration | What Google does | Correct approach |
|---|---|---|
Invalid code (en-uk, zh-cn misuse, region-only) | Ignores the invalid row, sometimes the whole set | ISO 639-1 language, ISO 3166-1 Alpha-2 region, hyphenated |
Tags in <body> or after markup errors close the head early | Never parses them | Place in <head> or use the HTTP header / sitemap method |
| Same URLs in HTML and sitemap with conflicts | Sees contradictory signals, discards | Pick one delivery method per cluster |
| Relative URLs | Resolution is unreliable | Always absolute, with protocol and host |
| hreflang pointing at redirecting or noindexed URLs | Drops those targets | Point only at final, indexable 200 URLs |
How to detect it
- Screaming Frog, Hreflang tab. The Incorrect Language & Region Codes and Non-200 Hreflang URLs filters surface invalid codes and bad targets immediately after a crawl.
- Validator. Run suspect URLs through an hreflang validator; it flags malformed codes, wrong placement, and mixed-method conflicts with specific error lines.
- View source. Confirm the tags actually sit inside
<head>and that no earlier markup error closed the head prematurely, which silently pushes them into the body. - Search Console. The international targeting and page indexing reports report unknown language codes and untrusted hreflang, corroborating the crawl findings.
How to fix it
- Audit every code against ISO 639-1 (language) and ISO 3166-1 Alpha-2 (region). Kill invented combos like
en-uk. - Consolidate to one delivery method. If you are torn between HTML and sitemap, the implementation guide lays out which suits your scale.
- Verify placement. Head-only for the
<link>method, and make sure no broken tag above it closes the head early. - Point at clean targets: absolute, indexable, 200-status URLs, never a redirect chain or a noindexed page.
- Recrawl and revalidate until the error filters come back empty.
When two rows genuinely disagree about which URL serves a language, that is its own diagnosis in conflicting hreflang entries. If the misconfiguration turns out to be a missing return reference rather than a bad code, see missing self-referencing hreflang.
FAQ
Why is misconfigured hreflang worse than having none?
None is a clean slate Google fills with its own logic. Misconfigured markup actively misleads the crawler, wastes budget on rows it cannot use, and hides the problem behind tags that look present in the source.
Is en-uk really wrong?
Yes. The language is en, but the United Kingdom's ISO country code is gb, so the valid value is en-gb. en-uk is a non-existent code Google discards.
Can I use both HTML tags and sitemap hreflang?
Pick one per cluster. Running both invites the two sources to drift apart, and once they conflict, Google stops trusting either. Consistency beats redundancy here.
Does capitalization matter in the codes?
Google is case-insensitive on the values, but the separator must be a hyphen, not an underscore, and the format language-first is non-negotiable. Stick to lowercase language, uppercase or lowercase region, hyphenated.
My hreflang points to pages that redirect. Problem?
Yes. hreflang targets should be the final, canonical, indexable URLs. Pointing at a redirect or a noindexed page gets that alternate dropped from the cluster.
How do I handle Chinese, Norwegian, and other tricky codes?
These trip people constantly. Simplified Chinese is zh or zh-cn, traditional is zh-tw or zh-hant; Norwegian splits into nb and nn, not a bare no in most cases. When a language has script or dialect variants, check the ISO 639-1 list before you guess, because an invented shorthand gets the row discarded like any other invalid code.
Can a single markup error break every hreflang tag on the page?
It can. An unclosed tag earlier in the head can close the head element prematurely in the parsed DOM, shoving every hreflang <link> below it into the body where Google never reads them. Validate the whole head, not just the hreflang block.
Claude Vincent is a technical SEO consultant focused on crawlability, rendering, and AI-search visibility. He writes the field guides and case studies at SEO ProCheck, with a bias toward the durable, unglamorous work that decides whether search engines and AI answer engines can actually read and cite a site.
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