Technical SEO mistakes → create → barriers for search engines to crawl, render, and index your site, which reduces visibility and ranking potential.

Even a single blocked resource or canonical error can quietly sabotage months of SEO work. These issues don’t just lower rankings — they make Google blind to your content.

In this guide by Kasra Dash, we’ll cover the most frequent technical SEO mistakes, why they happen, and how to fix them — step by step.

→ For a complete diagnostic process, review your Technical SEO Audit and Fix Indexing Issues guides before making changes.

Technical SEO success depends on removing friction between your site and Googlebot.

1. Crawlability Mistakes

If Googlebot can’t crawl your site, it can’t index or rank it. Many websites accidentally block access to important sections or waste crawl budget on non-value URLs.

Common Crawl Mistakes

• Blocking essential pages in robots.txt.
• Disallowing entire directories with Disallow: /.
• Forgetting to remove noindex after staging.
• Failing to submit updated XML sitemaps.

✅ Fix It:

• Check your robots.txt using Google Search Console → Robots.txt Tester.
• Keep your sitemap fresh and only include canonical URLs.
• Remove temporary “noindex” tags after deployment.

→ See detailed solutions in Fix Indexing Issues.

Crawl accessibility is the foundation of visibility.

2. Indexation Mistakes

Even if Google can crawl your site, it won’t index every page. Poor canonicalisation, thin content, or duplicate pages can prevent inclusion.

Common Indexation Problems

• Canonical tags pointing to non-existent URLs.
• Duplicate content across parameters (?sort= or ?filter=).
• Pages blocked in robots.txt but still linked internally.
• Thin or low-value content ignored by Google.

✅ Fix It:

• Implement correct Canonical Tags.
• Merge duplicates into one strong, indexable version.
• Improve page quality and depth — thin content won’t survive modern algorithms.

→ Validate progress in Fix Indexing Issues.

If your canonicals conflict with your sitemaps, you’re sending mixed signals to Google.

3. JavaScript and Rendering Errors

JavaScript rendering → affects → how Google sees and indexes your page.

Sites built on frameworks like React or Angular often depend on client-side rendering — which Googlebot may struggle to execute.

Common JavaScript Mistakes

• Relying solely on client-side rendering (CSR).
• Lazy-loaded content without fallbacks.
• Hidden meta or canonical tags injected post-render.
• Blocked JS or CSS files in robots.txt.

✅ Fix It:

• Use Server-Side Rendering (SSR) or pre-render tools like Rendertron.
• Provide <noscript> fallbacks for key content.
• Allow Googlebot access to all JS and CSS files.

→ Read JavaScript SEO for deeper optimisation steps.
→ Ensure mobile rendering parity in Mobile-First Indexing.

If Google can’t render your content, it can’t rank your site.

4. Site Speed and Core Web Vitals

Core Web Vitals → measure → how fast, stable, and responsive your website feels to users.

Slow websites not only frustrate visitors but also lower your organic visibility through Google’s Page Experience signals.

Key Performance Metrics

Metric	Target	Impact
LCP (Largest Contentful Paint)	≤ 2.5s	Loading performance
INP (Interaction to Next Paint)	≤ 200ms	Interactivity
CLS (Cumulative Layout Shift)	≤ 0.1	Visual stability

Common Speed Mistakes

• Oversized hero images or uncompressed media.
• Excessive third-party scripts.
• Poor hosting or unoptimised caching.

✅ Fix It:

• Compress images (WebP/AVIF) and serve via CDN.
• Minify CSS/JS and remove unused code.
• Upgrade hosting or enable server caching.

→ Learn full optimisation techniques in Core Web Vitals and Website Speed SEO.

Speed fixes aren’t cosmetic — they directly influence rankings and conversion rates.

5. Canonical and Duplicate Content Issues

Canonicalisation errors confuse Google about which version of a page to index.

Frequent Mistakes

• Missing or conflicting canonical tags.
• Cross-domain duplicates (e.g., HTTP vs HTTPS).
• Incorrect canonicals on paginated series.

✅ Fix It:

• Use self-referencing canonicals where possible.
• Point duplicate or parameterised URLs to a single canonical target.
• Verify all canonicals resolve with a 200 status code.

→ Learn full implementation strategy in Canonical Tags.

Canonical clarity consolidates authority — confusion splits it.

6. Crawl Budget Waste

Crawl budget waste occurs when Googlebot spends time on low-value URLs — filters, tags, or duplicate variations — instead of important content.

Signs of Crawl Waste

• High “Discovered – not indexed” count.
• Crawled URLs that never generate impressions.
• Infinite scroll or faceted navigation loops.

✅ Fix It:

• Block non-indexable parameters in robots.txt.
• Consolidate filters with canonical tags or noindex.
• Prioritise internal links to key pages.

→ Learn crawl efficiency techniques in Crawl Budget.

Efficient crawling maximises visibility without extra effort.

7. Security and HTTPS Issues

HTTPS → signals → trust and security to both users and search engines.

Incorrect SSL configurations or mixed-content warnings can harm credibility and rankings.

Common HTTPS Problems

• Mixed content (secure + insecure resources).
• HTTP pages redirecting improperly.
• Expired SSL certificates.

✅ Fix It:

• Force HTTPS via 301 redirects.
• Update all internal and canonical links to HTTPS.
• Renew SSL certificates before expiry.

→ Validate redirects and certificates during every Technical SEO Audit.

Security errors are small technical flaws with major trust consequences.

8. Structured Data and Schema Errors

Structured Data → enhances → how your content appears in search.

However, missing or invalid schema can prevent rich results or even cause manual actions.

Frequent Schema Mistakes

• Invalid JSON syntax (missing commas/braces).
• Incomplete required properties.
• Mismatched schema vs visible content.

✅ Fix It:

• Validate markup using Google’s Rich Results Test.
• Ensure JSON-LD matches page content exactly.
• Fix syntax using the Schema Markup Guide.

→ Confirm crawl and render behaviour in JavaScript SEO.

Structured data only works when it reflects truth — markup integrity equals visibility integrity.

9. Prevention: How to Avoid Technical SEO Mistakes

Preventing technical SEO problems is far easier than fixing them later.

Maintenance Checklist

• Run a full Technical SEO Audit quarterly.
• Monitor crawl stats in Google Search Console.
• Set up crawl alerts in Screaming Frog or Sitebulb.
• Maintain a staging environment for testing updates.
• Validate schema, canonicals, and sitemaps before deploying.

Prevention saves rankings, bandwidth, and stress.

Summary: Avoid Mistakes, Protect Visibility

Avoiding technical SEO mistakes → keeps → your site stable, crawlable, and optimised for growth.

To recap:

• Fix crawl and index barriers early.
• Ensure accurate canonicalisation and schema.
• Maintain speed and mobile performance.
• Audit your site quarterly to catch regressions.

→ Ready to fix your site? Schedule a Technical SEO Audit today and safeguard your organic visibility.

Your rankings depend on precision — eliminate technical friction before it costs you growth.