What level is WCAG 4.1.1?

Level A. It sits under guideline 4.1 Compatible of the Robust principle.

What are common ways pages fail WCAG 4.1.1?

Duplicate `id` attributes break ARIA reference relationships. Unclosed tags confuse legacy assistive tech.

How do I fix WCAG 4.1.1 issues?

Run an HTML validator in CI. Avoid manual ID juggling — generate unique IDs.

4.1 Compatible · Robust

WCAG 4.1.1 Parsing

Level A

Markup must have no parsing errors that affect assistive tech (duplicate IDs, unclosed tags). Note: this criterion was withdrawn in WCAG 2.2; still in 2.1.

Common failures

Duplicate `id` attributes break ARIA reference relationships.
Unclosed tags confuse legacy assistive tech.

How to fix

Run an HTML validator in CI.
Avoid manual ID juggling — generate unique IDs.

Related criteria

WCAG 4.1.2 Name, Role, Value Level A