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Fix Duplicate URLs, Redirects and Canonical Problems in Next.js

Duplicate URL problems usually show up as one page reachable in several ways, redirect rules that keep changing, or canonical signals that no longer match the live route policy.

Fix duplicate URLs, bad redirects, and canonical mistakes before search engines and users keep landing on conflicting versions of the same page.

Short Answer

Redirect and canonical problems become commercial problems when users and search engines keep reaching different versions of the same content. Next.js can make that harder to reason about if URL rules are split across the app, platform, CMS, and CDN. The fix starts with one clear policy, then careful rollout across the layers that disagree.

Typical Symptoms

  • Duplicate URLs, conflicting canonicals, or trailing‑slash mismatches are appearing.
  • Redirect maps are incomplete, inconsistent, or difficult to trust.
  • The same content is reachable across multiple domains or URL states.

Likely Causes

  • URL policy changed during a migration or deployment without full follow‑through.
  • Redirect logic is split across platform, application, and CMS layers.
  • Canonical output does not match the actual preferred live URLs.

What I Look at First

  • Quick check: request the same priority URLs across slash, case, and domain variants and compare the final destination and canonical output.
  • Domain, trailing‑slash, and case‑handling rules across the stack.
  • Which route families are creating ambiguity for users and crawlers.

How I Help Fix This

  • Reduce the problem to one clear URL policy and implementation path.
  • Prioritise the highest‑risk redirect and canonical gaps.
  • Roll out fixes in a way that is measurable and safe.

When to Look at This

  • When migrations or platform changes introduced duplicate URL states that now affect visibility.
  • When redirect ownership is split across app, CDN, and CMS layers and nobody trusts the live policy.

What Gets Resolved

  1. Redirect chains, URL variants, canonicals, trailing slashes, and indexing signals are mapped before normalisation changes are shipped.

  2. Lost or underperforming URLs are mapped against rendered HTML and crawl or indexing signals.

  3. Redirect, canonical, sitemap, robots, metadata, and schema faults are separated.

  4. Fixes are prioritised by commercial search exposure and implementation risk.

  5. The team knows which evidence to re‑check after release.

How This Usually Works

  1. Technical Diagnostic

    A focused review of affected routes, templates, deployment behaviour, crawl signals, CMS behaviour, performance bottlenecks, or code paths, followed by a prioritised fix plan the team can take into delivery.

  2. Recovery Sprint

    A short, concentrated engagement for a defined technical SEO, performance, CMS, Vercel, migration, or production issue where the business needs the cause isolated and the first fixes moved quickly.

Get in touch about the recovery

A short description of the affected route, Search Console signal, or production symptom is enough. I'll read it and suggest the next step.

Get in touch

Related Project Work

  1. Screenshot of the Nando’s website; part of John Kavanagh's development portfolio.

    A Complete Migration and Replatform for Nando’s

    On Nando’s, the migration tied structured data, restaurant‑page improvements, local discovery, and measurable search uplift into one Next.js and Vercel delivery.

    View project

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