How to fix html lang on OpenCart

Steps for OpenCart

1. In OpenCart, the HTML wrapper is in the theme's header template file, typically catalog/view/theme/<your-theme>/template/common/header.twig (or header.tpl for older versions).
2. Open that file via Admin › Design › Theme Editor, or via FTP.
3. Find the <html opening tag and add the lang attribute. OpenCart passes language data to templates; use the language code variable, e.g.: <html lang="{{ language_code }}"> or hard-code your language: <html lang="en">.
4. Save the file and clear the OpenCart cache via Admin › Dashboard › cog icon › Refresh, then verify via View Page Source.

What is html lang?

Every web page starts with an opening `<html>` tag. Adding a `lang` attribute to it — for example, `<html lang="en">` for English — tells browsers, screen readers, and search engines what human language the page is written in. It is a one-line change in your theme or template, and it is one of the most foundational requirements of modern web standards. The value uses a standard two-letter (or extended) language code such as `en`, `fr`, `de`, `es`, `ja`, or `zh-Hans`.

Screen readers used by visually impaired shoppers rely on the `lang` attribute to choose the correct pronunciation engine — without it, your content may be read aloud in the wrong language, making your store inaccessible. Accessibility laws in many jurisdictions (ADA in the US, EN 301 549 in the EU, AODA in Canada) treat a missing `lang` attribute as a conformance failure, creating real legal exposure. Search engines also use this signal to understand which market a page targets, which influences how and where your pages appear in regional search results. Fixing it is a quick win that simultaneously reduces legal risk, improves usability for millions of shoppers with disabilities, and reinforces your international SEO targeting.

See the complete Html lang guide for every platform and the full background.