hreflang in Next.js 16: 3 mistakes that quietly delete your translated pages from Google (opens in new tab)

TL;DR — If you ship the same page in several languages, hreflang is what tells Google "these are translations of each other, not duplicates." Three mistakes make Google ignore (or actively penalize) your setup: a non-reciprocal cluster, hreflang pointing at URLs that 404, and a canonical that points at the English master instead of the page itself. None throws an error. None fails your build. You only catch them by reading the rendered . Here's the Next.js 16 Metadata API pattern that a...