Language
html-xml-lang-mismatch
WCAG 3.1.1 Language of Page Level A
Who this affects
The lang and xml:lang attributes disagree, so the language announced depends on the tool.
How to fix it
Make both attributes the same, or keep only lang.
How much work is it?
Usually a template or design change. That is a rough guide for planning, not an estimate for your codebase. A single content edit repeated across a template is a template change.
What a person still has to check
Passing this rule does not mean 3.1.1 passes. Automation checks part of the criterion, and the rest is a judgement:
A person has to review this criterion against the site by hand.
Read 3.1.1 Language of Page in plain language
Where this check comes from
This is an axe-core rule. We run axe in a real browser on every page we scan. Deque’s reference for html-xml-lang-mismatch
Find out whether your site does this
A scan checks this rule on every page it visits, and shows you the code and a screenshot of each place it fires.