1.8 URL structure & internationalisationHighVerified
hreflang not reciprocal
What it is
Return tags missing between versions.
Why it matters
Non-reciprocal hreflang is ignored, defeating the implementation.
How to fix it
Ensure every version references all others, including itself.
Impact
Medium-high. Direct.
Evidence
hreflang must be reciprocal. Google Search Central, Tell Google about localized versions (hreflang)