The situation occurs when there's an hreflang declaration on a webpage, but the referenced alternate URL fails to include a corresponding hreflang attribute pointing back to the original.
Why is this important?
Correct utilization of hreflang annotations aids search engines in understanding the relationship between webpages aimed at different languages or regions. Proper, bidirectional (reciprocal) hreflang tags ensure that search engine indexing functions optimally.
For instance, if a webpage in English references its French counterpart via hreflang, it's imperative that the French page similarly references the English page. The absence of this mutual reference could lead to search engines disregarding the hreflang guidance.
What does the Optimization check?
The Optimization will be activated whenever a URL found has hreflang tags pointing outwards, yet lacks a matching inbound hreflang tag from at least one of the specified alternate URLs.
Examples that trigger this Optimization:
Take into account the URL: https://example.com/en/page-a/
This URL would trigger the Optimization if it contains the following hreflang annotations:
<link rel="alternate" href="https://example.com/fr/page-a/" hreflang="fr-fr" /><link rel="alternate" href="https://example.com/es/page-a/" hreflang="es-es" /><link rel="alternate" href="https://example.com/de/page-a/" hreflang="de-de" />
and suppose that the URL https://example.com/fr/page-a/ incorporates this hreflang:
<link rel="alternate" href="https://example.com/es/page-a/" hreflang="es-es" /><link rel="alternate" href="https://example.com/de/page-a/" hreflang="de-de" />
However, it does not provide a reciprocal hreflang tag linking back to the original /en/ page.
How do you resolve this issue?
The bidirectional nature of hreflang is critical for its function. Therefore, if you wish for hreflang to be effectively utilized, you must integrate the missing hreflang annotation for each non-reciprocal page.