bug: static rendered html lang is always "en" + missing "hreflang" #5086

bguiz · 2026-04-02T09:10:31Z

bguiz
Apr 2, 2026

Steps to reproduce

In docs.json configure multiple languages via navigation.languages based on instructions in https://www.mintlify.com/docs/guides/internationalization
- Includes Korean language pages under /ko/*

Problem 1

Visit https://{YOUR_MINTLIFY_DOMAIN}/ko in Chrome
Use "View Source" to view static render from server
Use DevTools to view dynamic render in browser (DOM)
Observe that the dynamic render has the <html /> tag's lang property's value as ko --> Correct behaviour
Observe that the static render has the <html /> tag's lang property's value as en --> Wrong behaviour

Problem 2

Visit https://{YOUR_MINTLIFY_DOMAIN}/ in Chrome
Use "View Source" to view static render from server
Observe that <link rel="alternate" hreflang="ko" href="{YOUR_MINTLIFY_DOMAIN}/ko/" /> is not present
Observe that <link rel="alternate" hreflang="x-default" href="{YOUR_MINTLIFY_DOMAIN}/" /> is not present

Observations

Problem 1

Therefore conclusion is that there is a bug where the pages are initially rendered with the default/ canonical language (en) and only updated in the browser
This is problematic from an SEO/ GEO perspective as it could result in:
- De-ranking due to duplicate content penalties
- Confusion (which page to use?) when gen AI tools are retrieving/ citing information from the site
- Excessive context bloat (resulting in poor quality result) when gen AI tools are retrieving/ citing information from the site

Problem 1 - Actual Outcome

Static render from server (wrong):

<!DOCTYPE html><html lang="en" class="__variable_47c970 __variable_3bbdad dark" data-banner-state="visible" data-assistant-state="closed" data-page-mode="none">

Dynamic render in browser (correct):

<!DOCTYPE html><html lang="ko" class="__variable_47c970 __variable_3bbdad twoslash-dark dark" data-banner-state="hidden" data-assistant-state="closed" data-page-mode="none" style="color-scheme: dark; --assistant-sheet-width: 0px; --banner-height: 0px; --sidenav-move-up: 0px;">

Problem 1 - Expected Outcome

Static render from server (correct):

<!DOCTYPE html><html lang="ko" class="__variable_47c970 __variable_3bbdad dark" data-banner-state="visible" data-assistant-state="closed" data-page-mode="none">

Dynamic render in browser (correct):

<!DOCTYPE html><html lang="ko" class="__variable_47c970 __variable_3bbdad twoslash-dark dark" data-banner-state="hidden" data-assistant-state="closed" data-page-mode="none" style="color-scheme: dark; --assistant-sheet-width: 0px; --banner-height: 0px; --sidenav-move-up: 0px;">

Problem 2

This is problematic from an SEO/ GEO perspective as it could result in:
- De-ranking due to duplicate content penalties

Problem 2 - Actual outcome

<link rel="canonical" href="{YOUR_MINTLIFY_DOMAIN}/ko"/>
<link rel="alternate" type="application/xml" href="/sitemap.xml"/>

Problem 2 - Expected Outcome

<link rel="canonical" href="{YOUR_MINTLIFY_DOMAIN}/ko"/>
<link rel="alternate" type="application/xml" href="/sitemap.xml"/>
<link rel="alternate" hreflang="en" href="{YOUR_MINTLIFY_DOMAIN}/" />
<link rel="alternate" hreflang="ko" href="{YOUR_MINTLIFY_DOMAIN}/ko/" />
<link rel="alternate" hreflang="x-default" href="{YOUR_MINTLIFY_DOMAIN}/" />

Context

I have translated pages in my docs where:

/*: English
/ko/*: Korean
... etc

References

https://www.semrush.com/blog/hreflang-attribute-101/

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Mintlify

bug: static rendered html lang is always "en" + missing "hreflang" #5086

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Mintlify

bug: static rendered html lang is always "en" + missing "hreflang" #5086

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bguiz Apr 2, 2026

Steps to reproduce

Problem 1

Problem 2

Observations

Problem 1

Problem 1 - Actual Outcome

Problem 1 - Expected Outcome

Problem 2

Problem 2 - Actual outcome

Problem 2 - Expected Outcome

Context

References

Replies: 0 comments

bguiz
Apr 2, 2026