The recurring, high-cost mistakes we see again and again — most of them silent, most introduced by a deploy or migration. Here's what each one does to your rankings and how to catch it before it costs you.
The worst SEO mistakes are silent. The page still loads, nothing looks broken, and the traffic drop arrives days later once search engines re-crawl — by which point the cause is buried. That delay is exactly why these need monitoring, not just a manual glance.
These remove pages from search entirely.
A staging noindex or CMS toggle that ships to production deindexes every page using that template at once. The single most common SEO disaster. How to catch it →
Canonicalising to a redirect, a 404, or every page to page 1 tells Google to index a different (or dead) URL, removing your real page. Canonical mistakes →
robots.txt doesn't deindex — it just stops Google seeing your noindex, leaving pages in the index with no description. The robots.txt trap →
Important URLs that started erroring drop out of the index. Always re-check status codes after a move.
These waste the ranking strength you've already earned.
Links to 404s waste crawl budget and leak link equity into dead ends. Why broken links hurt →
Pages nothing links to are barely discovered and starved of authority. Orphan pages →
Multi-hop redirects waste crawl budget and risk equity loss; loops take a page offline entirely. Redirect chains →
A temporary redirect keeps the old URL indexed and stalls the transfer of authority to the new one. 301 vs 302 →
Linking to a URL that redirects wastes a hop on every crawl and click. Link to the final URL directly.
Generic anchors waste the topical signal a link could pass. Describe the destination. Anchor text →
These muddy how pages are understood or felt.
Repeated tags across pages dilute clarity and signal templated content. Fix titles & descriptions →
Redirects, 404s, and noindex pages in the sitemap send contradictory signals to crawlers. Sitemap best practices →
Failing LCP, CLS, or INP on mobile costs both a ranking signal and real conversions. Core Web Vitals →
On multilingual sites, missing return tags and invalid codes serve the wrong-language page or cause versions to compete. hreflang guide →
JSON-LD errors throw warnings in Search Console and block rich results. Validate any schema you ship, and don't invent properties that aren't in the schema.org vocabulary.
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