The canonical tag error was the most common finding, appearing on 31 of the 47 sites. The typical error was missing canonicals on paginated listing pages — the second and third pages of a category archive had no canonical tag at all, causing search engines to treat each as a unique page. JekCMS generates canonicals automatically, but the SITE_URL constant must match the live domain exactly, including the https:// prefix and any www prefix.

Hreflang: The Reciprocal Link Problem

Hreflang misconfigurations came second, affecting 24 sites. The typical error was a Turkish language page referencing an English hreflang URL that did not exist — creating an orphaned pair. Both the x-default tag and each language variant must reference the other in their respective hreflang declarations. A missing reciprocal link invalidates both sides. Google Search Console reports this as a "Return tag missing" error.

Sitemaps Pointing to Redirects

Sitemap issues were the third major finding. Several sites had sitemap.xml entries pointing to URLs that return 301 or 302 redirects rather than 200. Search engines follow these redirects when crawling, but they record the final destination URL as the canonical — not the URL listed in the sitemap. Regenerate your sitemap after any URL structure change.

Migration History Matters

The industries with the highest density of errors were news sites and e-commerce integrations — both categories had migrated from other platforms and inherited structural problems. Fresh JekCMS installations with no migration history had on average 2.1 errors per site, compared to 9.4 for migrated sites.