Missing HTML lang attribute
This means that the URL in question has not defined the language/region attribute using HTML lang.
Why is this important?
While Google and Yandex use hreflang to determine which URLs to display in regional search results, some search engines, such as Bing, rely on the language specified in the HTML - commonly referred to as HTML lang.
If a URL does not set a HTML lang value, you may find that the language/region is not correctly interpreted by all search engines, which may result in the incorrect page being served in localised search results.
What does the Hint check?
This Hint will trigger for any URL which has no document location.
Examples that trigger this Hint:
Consider the URL: https://example.com/en/page-a/
The Hint would trigger for this URL if it does not specify HTML language, using any of the methods below;
The "content-language" meta tag in the <head>:
The <html lang> element in the <head>:
The <title lang> element in the <head>:
How do you resolve this issue?
Some search engines rely on HTML lang (instead of hreflang) to determine the language/region of a page, so if this is missing the language may not be correctly interpreted.
If this is an important traffic source (e.g. if the website exists in a market with high Bing usage), add the HTML lang to all pages that have hreflang.