Crystal Ball checks covered

SITEMAP_UNSUPPORTED_FORMAT, SITEMAP_PARSE_ERROR, SITEMAP_XML_INVALID

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What this warning means

This warning means the sitemap URL was reachable, but the file did not look like a supported XML sitemap to the crawler or testing tool.

  • The most common issues are malformed XML, unexpected bytes before the XML declaration, an HTML error page served at sitemap.xml, an unsuitable response type, or invalid sitemap namespaces.

Common causes

Common causes include uploading the wrong file, serving a cached old sitemap, adding a byte order mark before the XML declaration, using smart quotes in XML, returning a branded HTML page instead of XML, or mixing image sitemap markup into a plain sitemap incorrectly.

  • The first bytes should be the XML declaration or a valid XML root.
  • The server should return a 200 response for the sitemap URL.
  • Every loc must be an absolute canonical URL.

How to fix it

Regenerate the sitemap as clean UTF-8 XML, validate it locally, upload it to the active document root, then fetch it in a browser and with a header check.

  • Keep the main sitemap and image sitemap valid against their own namespaces.
  • Do not include HTML, Markdown, comments before the XML declaration, or unsupported tags.
  • Update robots.txt to point to the canonical sitemap URL.

How to verify

Open the sitemap URL directly and inspect both the response status and source. It should return the intended sitemap content, not an HTML error page or redirect destination. Then validate it with an XML parser and resubmit it in Search Console.

  • Check sitemap.xml.
  • Check robots.txt sitemap lines.
  • Check that the submitted sitemap URL exactly matches the live file.

FAQ

Can a sitemap be readable in the browser but invalid to Google?

Yes. Browsers are forgiving. Search Console expects a supported sitemap format and valid XML structure.

Should image sitemap entries go in the main sitemap?

They can, but the XML namespace must be correct. A separate image sitemap is often easier to maintain.

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