SitemapScan Blog
Common Sitemap Validation Errors and How to Fix Them
Even small errors in your sitemap can cause search engines to skip it entirely. Here are the most common validation issues we detect — and exactly how to resolve each one.
Invalid XML structure
The most critical error. If your sitemap isn't well-formed XML, crawlers will reject the entire file. Common causes: unclosed tags, special characters like &, <, or > inside URLs without encoding, and incorrect namespace declarations.
URLs not using the correct protocol
Every URL in your sitemap must use the same protocol and domain as declared in your XML namespace. If your site is HTTPS, all URLs must start with https://.
Malformed lastmod dates
The lastmod field must follow the W3C Datetime format: YYYY-MM-DD or the full ISO 8601 format with time and timezone. Dates like '01/15/2024' or 'January 2024' will fail validation.
About this article
This article is part of the SitemapScan blog and covers XML sitemap, robots.txt, crawlability, or related technical SEO topics.
FAQ
What are the most common sitemap validation errors?
Typical problems include invalid XML, malformed dates, duplicate URLs, oversized files, protocol mismatches, and non-200 URLs inside the sitemap.
Can one sitemap error break the whole file?
Yes. A malformed XML structure or other critical format error can make the entire sitemap unreadable to crawlers.
Related pages
- What Is an XML Sitemap and Why Does It Matter for SEO? — An XML sitemap is one of the most fundamental technical SEO files on your website — yet many site owners overlook it entirely. Here's everything you need to know.
- Sitemap Index Files: A Guide for Large Websites — Once your site grows beyond 50,000 URLs, a single sitemap file won't cut it. Here's how to structure sitemap indexes properly for large e-commerce, news, and enterprise sites.
- Crawl Budget: What It Is and How Your Sitemap Affects It — Crawl budget is a finite resource that Googlebot allocates to your site. A poorly structured sitemap can waste it on low-value pages, leaving important content uncrawled.
- XML Sitemap Checker — Validate the topic against a live sitemap.
- Latest Sitemap Checks — See how similar sitemap patterns show up in the public archive.