Why do migrations go wrong (even with great teams)?
Website migrations are like moving houses, you know it’s going to be chaotic, things will inevitably go wrong, and yet you still have to do it. No matter how meticulously you plan, something always gets left behind or breaks in transit.
The frustrating part? Most migration disasters aren’t caused by incompetent teams or poor tools. They happen because there are simply too many moving parts. Developers rebuild templates, engineers configure new systems, content teams update copy, and SEO specialists map redirects, all on different timelines with different priorities.
While you can’t prevent all chaos, you can minimize the damage. This article identifies the most common migration pitfalls and provides practical frameworks to catch critical issues before they tank your visibility.
The core variables that define migration complexity
A lot of migration mistakes can be avoided with upfront planning, bringing different teams together to define variables and workflows early. Here are the general areas that come into play.
The scope of migration and the implications
CMS or tech stack change
Is the website switching CMS platforms? Will different sections use different systems? It’s fairly common for websites to run separate CMS platforms for their blog sections, for instance. SEOs need to identify what switching CMS means for information storage; does the new CMS have fields for all existing data?
For tech stack changes, a key consideration is whether the site is moving to Single Page Applications (SPAs). Switching web architecture influences programming language and framework choices, typically leaning toward JavaScript-based solutions, which have specific SEO implications.
Domain structure
Identify early whether the migration involves structural URL changes: domain name changes (rebranding, TLD switches like .com to .co.uk), folder name changes, or decisions between subfolders versus subdomains.
URL structure impacts hreflang implementation (whether cross-domain hreflang is needed), canonical updates, and redirect mapping complexity.
New design and page consolidations
Site migrations sometimes happen alongside redesigns, involving new wireframes and page reorganization across sections like collections, products, or blog pages. SEOs need to understand if all sections are moving or being selectively merged.
Does the new design involve different navigation depth, altered internal links, or component rebuilds? These changes affect breadcrumb structures and internal linking architecture.
Aligning stakeholders
After identifying these variables, align stakeholders on workflows for each item. Website migrations require coordination across multiple teams, so a RACI matrix can be invaluable.
RACI stands for Responsible, Accountable, Consulted, and Informed; it helps prevent confusion by mapping tasks against team members and defining who does what for each activity.
Common migration mistakes to avoid
Even when you consider the full scope of your migration and you’ve seemingly planned each step meticulously, I’ve still seen some of the following mistakes elude some of the most experienced SEOs. All this to say, it never hurts to be aware of what could happen and try to avoid it.
Mistake 1: Mixing human input with technical input
One of the most frequent and damaging errors in large-scale migrations is the conflict between manual SEO settings (human input) and automated platform logic (technical input). Here are two common examples.
[Case Study] Monitoring and optimization of a website redesign following a penalty
Manual input vs. automated canonical tags
During migration, conflicts often arise when canonical URL control shifts from a manual field in the old CMS (human input) to an automated function in the new platform (technical input).
In the old system, an editor manually enters the preferred URL into a dedicated field:
html
<link rel="canonical" href="https://example.com/category/product">
In the new CMS, the platform code automatically generates canonicals based on the URL structure it sees, including parameters:
html
<link rel="canonical" href="https://example.com/category/product?utm=google&session=123">
Without proper planning, these two scenarios collide, potentially creating canonical issues that dilute ranking signals.
Structured data markup management
It’s crucial to identify whether schema markups use microdata or JSON-LD format, as this determines the level of manual input required.
JSON-LD
The migration process involves identifying fields and data, then integrating them into the new CMS. The tech team builds scripts that dynamically pull information from the CMS database and inject structured data onto pages. Crucially, SEO and content teams must first identify and confirm the exact data source fields for every schema property, providing specifications for developers to implement correctly.
Microdata
In general, microdata requires higher maintenance, which is often the case for schemas with more variables, therefore, migrations often involve moving from microdata to JSON-LD. This requires editing or replacing every old HTML template to physically remove itemprop attributes, a labor-intensive process that needs careful tracking.
Mistake 2: Misaligned environments → regressions after launch
One of the trickier aspects of site migrations involves keeping staging and production environments properly aligned. When these environments have inconsistencies, testing can give misleading results, potentially leading to visibility issues once the site goes live.
Common areas where discrepancies occur include robots.txt files, hreflang implementations, redirect chains, and meta directives.
During development, it’s standard practice to block search engines from staging environments using noindex tags or Disallow: / in robots.txt. However, problems arise when these protective measures accidentally get pushed to production, signaling to Google that the entire site shouldn’t be indexed.
Similarly, if staging URLs become hardcoded into hreflang tags or canonical directives, this creates complications post-launch. When production pages point to staging.yoursite.com as the canonical version, search engines may honor those directives and consolidate ranking signals to URLs that eventually return 404 errors.
Mistake 3: Data loss or misalignment during CMS migration
The DOM scraping trap
In complex, multilingual setups, development teams often migrate content by scraping directly from the DOM or exporting from the live CMS database, operating under the assumption that what’s rendered is authoritative. This approach introduces multiple failure points that can compromise site integrity post-launch.
Common data integrity issues
Several critical problems tend to emerge from DOM-based migrations. Legacy URL structures and internal linking patterns frequently carry over unchanged, perpetuating outdated taxonomies or deprecated navigation hierarchies.
In international deployments, language variants may be incorrectly merged or duplicated. Consider scenarios where distinct hreflang clusters for fr-CA and fr-FR are inadvertently consolidated, breaking regional targeting and creating canonical conflicts.
Metadata schema misalignment is often detected too late. When CMS field architectures differ between platforms, critical SEO elements often fail to map correctly without SEO professional input.
Custom fields for meta robots directives, structured data vocabularies, or pagination annotations may be truncated, misnamed, or dropped entirely if the migration script lacks explicit field-level mapping logic.
The consolidation timing problem
Interteam timing does not always align for migrations and multi-market consolidations only amplify the problems associated with timing.
While developers work from a frozen export to ensure quality assurance stability, content teams and localization vendors continue updating production—refreshing product copy, correcting translations, or updating compliance language.
At launch, the new platform deploys what is essentially a stale snapshot, overwriting weeks of editorial work and requiring emergency post-launch remediation.
How to prevent all of the above with structured technical check-ins
Successful migrations require structured checkpoints embedded directly into project timelines, not bolted on as an afterthought. Treating SEO validation as discrete gates, with clear ownership, tooling, and pass/fail criteria, prevents issues from compounding across migration phases.
Phase 1: Pre-migration audit
Implement a baseline crawl audit capturing live state across all metadata layers: title tags, canonicals, hreflang clusters, robots directives, and internal link graphs.
Structure your migration around an explicit source-to-destination mapping manifest that documents field-level transformations per locale and template type. This baseline becomes your source of truth for validating migration completeness.
Phase 2: Staging validation
Before production deployment, validate staging environment parity against your baseline. Verify that page counts, template distributions, and URL structures match specifications. Critically, on launch day, audit robots.txt, meta robots tags, and canonical implementations to ensure staging-specific blocking directives haven’t leaked into production configurations.
Phase 3: Post-launch monitoring
Migration doesn’t end at deployment. Establish monitoring protocols tracking Google Search Console metrics: indexation status, Core Web Vitals, and crawl error patterns.
Monitor ranking positions for high-value keyword sets, flagging significant deltas that may indicate technical regressions. Track organic traffic segmented by folders or sections and market to isolate problem areas quickly.
Schedule review checkpoints at T+1, +7, +14, and +30 days post-launch to catch issues early and validate that your migration is performing as expected.
Closing thoughts
Website migrations will always involve some degree of chaos, that’s the nature of moving complex digital properties. But with proper planning, clear ownership, and structured validation gates, you can significantly reduce the risk of SEO disasters.
The key is treating SEO not as a post-launch checklist item, but as an integral part of the migration process from day one.
