Hreflang Mistakes That Break Multilingual Sites and How to Audit Them

One of the most frequent errors is the failure to use absolute URLs within the hreflang attributes. Search engines require the full web address, including the protocol (https) and domain name, to accurately identify the alternate version of a page. If a site uses relative paths like ‘/es/page’, the crawler may fail to resolve the link, rendering the entire hreflang cluster invalid. This often happens when developers copy code from staging environments to production without updating the URL structure to reflect the live domain.

Another widespread problem involves the lack of self-referencing tags. Each page in a multilingual cluster must include a tag that points to itself in addition to pointing to its alternates. For example, an English page must have an hreflang tag for ‘en’ that links to its own URL. Omitting this self-reference is a technical violation that can cause search engines to ignore the other language signals provided on that same page. In a typical account, this mistake occurs when the automation logic only focuses on the ‘other’ versions.

Absolute URLs provide a clear, unambiguous path for search engine bots to follow. In a multilingual setup, you might have subdomains like ‘es.example.com’ or subfolders like ‘example.com/es/’. By using absolute URLs, you eliminate the risk of the crawler misinterpreting a relative path based on the current directory. Moreover, absolute URLs are less prone to errors when content is shared across different platforms or when the site architecture undergoes changes that might affect how relative links are resolved by the browser or crawler.

For example, a Shopify store selling electronics across Europe might use different domains for different countries. Using relative URLs in such a complex environment could lead to the German version of a product page accidentally pointing to a non-existent path on the French subdomain. Standardizing on absolute URLs ensures that the search engine always has the exact destination. This practice is a fundamental requirement for maintaining a clean and error-free international SEO profile across diverse regions.

Hreflang requires specific formatting for language and region identification. You must use the ISO 639-1 format for languages and the ISO 3166-1 alpha-2 format for regions. A common mistake is using ‘en-UK’ for the United Kingdom, whereas the correct code is ‘en-GB’. Another error is trying to use a region code by itself. You cannot simply use ‘hreflang=”us”‘ because region-only codes are invalid. It must be ‘en-us’ or another language combined with the region code to be valid.

When targeting a broad language group without a specific region, use the language code alone, such as ‘fr’ for all French speakers globally. If you want to target French speakers specifically in Canada, you would use ‘fr-ca’. It is vital to remember that the language code always comes first. Reversing the order or using the wrong character like an underscore instead of a hyphen will result in the tag being ignored. Accuracy here is essential because search engines will not attempt to guess your intention if the code is malformed.

The x-default attribute is a specialized value used to identify a page that is not targeted at any specific language or locale. It is most commonly applied to homepage selectors or landing pages where a user is prompted to choose their country or language. By defining an x-default page, you tell search engines which version to show to users whose language settings do not match any of the other specified hreflang values. This prevents the search engine from making an incorrect guess about which localized page to display.

Using x-default is particularly helpful for global brands that want to maintain a neutral entry point for their website. Additionally, it helps provide a safety net for users in regions where you do not have a dedicated translation. For instance, a user in Brazil might be shown the x-default global English site rather than the Spanish version intended for Mexico if a Portuguese version does not exist. This attribute should always point to a page that provides a general, useful experience for any international visitor.

Auditing a multilingual site requires a combination of automated tools and manual spot-checking. Large-scale websites often use XML sitemaps to manage hreflang rather than on-page HTML tags, as this centralizes the management of thousands of links. Regardless of the method used, the audit should focus on identifying broken links, non-reciprocal tags, and syntax errors in the ISO codes. Alien Road recommends performing these audits after every major site update or migration to ensure the international signals remain intact and functional.

• Use a crawler to identify pages with missing self-referencing hreflang tags across the site.
• Check for ‘return tag’ errors where the alternate page does not point back to the source URL.
• Verify that all URLs in the hreflang set are identical across all versions of the page group.
• Scan for invalid ISO codes and region-only declarations that lack a language prefix.
• Ensure that no URLs in the hreflang tags are being redirected or returning 404 status codes.
• Check that the x-default tag is pointing to the correct global or neutral landing page.