Technical fix guide
Hreflang Syntax Invalid
Hreflang tags are present but contain syntax errors such as invalid language codes or malformed URLs.
Issue ID: TECH-HREFLANG-SYNTAX-001
Severity: minor
Impact: Med
Effort: S
Use this article when
- You need deeper remediation guidance than the issue card can show.
- You want CMS-specific steps before handing the fix to a developer.
- You want a repeatable re-check path after shipping the change.
What this issue is
Hreflang tags are present but contain syntax errors such as invalid language codes or malformed URLs.
Why it matters
Hreflang tags are present but contain syntax errors such as invalid language codes or malformed URLs. This affects crawlability, rendering, and whether the site can be interpreted correctly by search engines.
How we detect it
- FreeSiteAudit flags this issue when the rule for TECH-HREFLANG-SYNTAX-001 fails and the page evidence points to Head metadata.
- You can usually confirm this by checking the page source or the relevant page settings inside your CMS.
Evidence examples
Check the affected page source, rendered output, or relevant CMS setting to confirm the missing or incorrect element.
How to fix it
- 1Use valid ISO 639-1 language codes (e.g., "en", "es", not "english")
- 2Optionally combine with ISO 3166-1 Alpha 2 region (e.g., "en-US", "es-MX")
- 3Ensure hreflang URLs are fully qualified (absolute URLs)
How to re-check it
- Validate hreflang tags using a hreflang checker tool
Related tools
This issue is best verified with the full FreeSiteAudit crawl rather than a single-point mini tool.