[lang] attributes do not have a valid value

To ensure correct pronunciation, screen readers use a different sound library for each language they support. Screen readers can switch between these language libraries easily, but only if a web page specifies which language to read for a given piece of content.

If the language changes within your page, you must specify a valid BCP 47 language to ensure that the section in the new language is pronounced correctly.

How the Lighthouse invalid lang attribute audit fails #

Lighthouse flags elements that have a lang attribute with an invalid value:

How to fix invalid lang attribute values #

Use only valid BCP 47 language codes in all lang attribute values.

Resources #

• Source code for [lang] attributes do not have a valid value audit
• lang attribute must have a valid value (Deque University)