Technical SEO Troubleshooting Guide
Technical SEO issues are silent — until traffic drops. This guide is the diagnostic flow we run when rankings slip without a content reason, organized by how often each issue is the actual culprit.
Start with crawl and indexation
Most technical regressions are noindex tags, robots.txt blocks, or canonical changes shipped during a release. Confirm Google can crawl and index the affected URLs before debugging anything else.
Canonical chains and conflicts
Canonical pointing to a 301 that points elsewhere = signal lost. Canonical to a noindex page = page gets dropped. Check that every canonical resolves to a 200 indexable URL in one hop.
Redirect loops and chains
Long redirect chains (3+) leak link equity and slow crawl. Loops drop the URL entirely. Audit redirects after every site migration.
JavaScript rendering issues
If content only appears after JS executes, confirm Google renders it. Use URL Inspection in Search Console and check the rendered HTML. If key content is missing, switch to SSR or pre-rendering for that template.
Schema errors
Invalid schema isn't penalized but it disqualifies you from rich results. Validate with Google's Rich Results Test, not just Schema.org's validator — Google is stricter about required fields.
Core Web Vitals regressions
Sudden CWV drops are usually one of: a new third-party script (LCP/INP), an unsized image (CLS), or a font swap (CLS). Bisect by deployment date.
Server-side issues
5xx spikes, slow TTFB, and certificate issues all suppress crawl. Confirm in server logs and Search Console crawl stats, not just synthetic monitoring.
Troubleshooting checklist
- URL Inspection confirms indexable + rendered
- Canonical resolves to 200 in one hop
- No redirect chain longer than 1 hop
- JS-rendered content visible in rendered HTML
- Schema validates in Rich Results Test
- CWV regressions bisected to a deployment
- Crawl stats and 5xx logs reviewed
Tools used in this workflow
Frequently asked questions
Rankings dropped overnight — where do I look first?
Check for accidental noindex tags or robots.txt changes shipped in the most recent release. That's the cause maybe 60% of the time.
How do I tell if it's a technical issue vs a content issue?
Technical issues affect template-wide ranking patterns (every product page drops). Content issues affect individual URLs. Group the affected URLs first — the pattern reveals the cause.
Should I disavow toxic links?
Rarely. Google ignores most spam automatically. Disavow only for confirmed negative SEO attacks or a manual penalty referencing links.