Invalid page language code

Message shown by axe and Lighthouse: <html> element must have a valid value for the lang attribute · html-lang-valid · WCAG 3.1.1

What it means and why it matters

An invalid lang value is ignored by assistive technology (WCAG 3.1.1).

How to fix it

Use a valid code such as en, de, fr or de-DE.

Code example

Before

<html lang="english">

After

<html lang="en-GB">

All accessibility errors