Rules / canonical rules

canonical.href.lowercase

Default

warn

Plugin

canonical

The canonical href has no uppercase letters.

Why: URL paths are case-sensitive, so /About/ and /about/ are different URLs. Lowercase URLs avoid two versions of one page.

The rule warns, and does not fail. Google asks for one case, not for lowercase.

When off: canonical links with uppercase letters pass.

<!-- ✗ Fails -->
<link rel="canonical" href="https://example.com/About/" />

<!-- ✓ Passes -->
<link rel="canonical" href="https://example.com/about/" />

References

• Google: URL structure: URLs are case-sensitive. Google asks for one case, not for lowercase, so the rule warns.