hreflang attribute not lowercased after build

[ihmpavel]

Hi, I came across different behavior of hrefLang

The attribute should be lowercased after ssr render, but is not changed

Example

<link
  rel='alternate'
  hrefLang='en'
  href='...'
/>

Expected output

<link
  rel='alternate'
  hreflang='en'
  href='...'
/>

Is is a bug?

(I know HTML attributes are case insensitive, but some crawlers are unable to parse HTML with hreflang which is not lowercased)

[princetanwar]

Hi @ihmpavel,

I'm also facing the same issue did you find any solution?

when I forcefully make it "hreflang" it shows correctly in the page source but it is removed in the inspect element.

[eliawk]

Yep, same problem here!

[kliatskiidenis]

Greetings
Has anyone found a solution, is this not a problem, because I, too, am developing on Nextjs 14 with app routing, I do as indicated in the official documentation and I get hrefLang instead of hreflang (in lower case)

[hdodov]

I can reproduce this on both Next 14.2.11 (latest 14 release at the time of writing) and Next 15.0.0-canary.156.

@leerob could you turn this discussion to an issue? The HTML spec defines a hreflang attribute, not a hrefLang one.

[todor0v]

@hdodov FYI, there is an existing PR that has not been merged yet.