How to migrate a site | Lillian Purge

How to Migrate a Site

I have migrated hundreds of websites over the years, from small brochure sites and ecommerce stores to large content heavy platforms with tens of thousands of URLs, and if there is one thing I believe strongly, it is this. A site migration is never just a technical task. It is a business critical change that affects visibility, trust, revenue, and long term growth.

In my opinion, most site migrations fail not because of bad intentions or lack of effort, but because people underestimate how many moving parts are involved and how closely SEO, UX, infrastructure, and content are tied together. A migration done well can improve performance, clarity, and scalability. A migration done poorly can wipe out years of organic growth almost overnight.

This article explains how to migrate a site in a structured, practical, and realistic way. It is written for business owners, marketers, and decision makers who want to understand what actually matters, what order things should happen in, and how to make good decisions before, during, and after a migration.

Everything here is grounded in real world UK experience, not idealised checklists or developer only guidance.

what a site migration actually is

A site migration is any significant change that affects how users or search engines access or understand your website.

From experience, migrations include far more than just changing a domain.

Common migration types include:

Changing domain name
Moving from http to https
Changing CMS or platform
Major redesign or restructure
Changing URL structure
Merging multiple sites into one
Splitting one site into several
Moving hosting or infrastructure

The key point is this. If URLs change, content changes, structure changes, or how Google accesses the site changes, you are performing a migration whether you label it as one or not.

Understanding that scope early is essential.

why migrations are risky for SEO

Search engines build understanding slowly.

From experience, Google develops trust in a site through consistent signals over time. When you migrate a site, you are changing many of those signals at once.

If Google cannot clearly map the old site to the new one, it has to reassess large parts of your presence. That reassessment can lead to temporary or permanent ranking loss.

In my opinion, the goal of a migration is not to trick Google into thinking nothing has changed. It is to make changes obvious, logical, and well signposted so trust transfers smoothly.

SEO during a migration is about clarity, not cleverness.

when migrations go wrong most often

The most common failures I see come from one of three places.

SEO is brought in too late
The migration is rushed
Decisions are made in isolation

From experience, migrations planned purely by developers or designers often miss search implications. Migrations driven only by marketing often miss technical realities.

A successful migration sits at the intersection of business goals, SEO understanding, and technical execution.

deciding whether you should migrate at all

Before talking about how to migrate a site, it is worth asking whether you actually should.

From experience, some migrations are unnecessary or premature.

Valid reasons to migrate include:

A platform that no longer scales
Severe technical debt
Rebranding or business change
Security or compliance issues
Performance limitations
Major UX problems

Invalid reasons often include boredom with design, copying competitors, or vague hopes of SEO improvement.

A migration always carries risk. There should be a clear business justification.

defining success before you start

One of the most important steps is defining what success looks like.

From experience, vague goals lead to poor decisions.

You should be clear on:

What must not be lost, such as rankings, traffic, or leads
What should improve, such as speed, clarity, or conversion
What can change safely, such as design or navigation

Without this clarity, trade offs are made blindly.

auditing the current site properly

Before migrating anything, you need to understand what you already have.

From experience, many migrations fail because people do not know which pages drive value.

A proper audit should identify:

Top traffic pages
Top converting pages
High value backlinks
Content that ranks well
Pages with historical importance

This audit informs which URLs must be protected at all costs and which can be retired or consolidated.

Never assume everything can be treated equally.

understanding your current URL structure

URL structure is one of the most sensitive elements in a migration.

From experience, unnecessary URL changes cause more harm than almost anything else.

If URLs do not need to change, do not change them.

If they must change, they must be mapped precisely.

Every old URL should have a clear destination on the new site or a justified reason for removal.

planning redirects properly

Redirects are the backbone of a safe migration.

From experience, redirects are often treated as an afterthought. They should be planned before anything goes live.

Every old URL that has value should redirect to the most relevant new URL.

Redirects should be:

One to one where possible
301 permanent redirects
Implemented server side
Tested before launch

Chaining redirects or using blanket redirects damages clarity and trust.

why redirect logic matters more than redirect volume

It is not about redirecting everything somewhere.

From experience, redirecting unrelated pages to the homepage is a common and damaging mistake.

Google expects relevance.

If an old blog post about one topic redirects to an unrelated page, trust is lost.

Relevance in redirect mapping protects rankings far better than sheer coverage.

handling content changes during a migration

Content changes often happen alongside migrations.

From experience, this is where things get risky.

Changing design, structure, and content all at once makes it harder to diagnose issues later.

Where possible, separate concerns.

If content must change, ensure that key topics, intent, and internal linking are preserved.

SEO content should not be rewritten casually during a migration.

migrating platforms or CMS

Platform migrations are especially complex.

From experience, common issues include:

Different URL handling
Different canonical logic
Different internal linking behaviour
Different pagination or filtering
Different metadata defaults

Assume nothing carries over automatically.

Everything should be checked explicitly.

staging environments and SEO risk

Staging environments are useful but dangerous.

From experience, staging sites often get indexed accidentally.

This creates duplicate content, confusion, and ranking loss.

Staging environments should be blocked from indexing properly using noindex and authentication where possible.

Removing these protections before launch is critical.

technical checks before launch

Before launch, several technical elements must be confirmed.

From experience, these include:

Correct canonical tags
Correct indexation directives
Clean internal links
Consistent trailing slash handling
Correct protocol and hostname
Functional redirects

Skipping these checks often leads to preventable problems.

launching the migration

Launch day should be boring.

From experience, a calm launch indicates good preparation.

On launch, you should:

Confirm the new site is accessible
Confirm redirects work as planned
Confirm old URLs resolve correctly
Confirm analytics and tracking
Confirm Search Console access

Avoid making additional changes during launch if possible.

monitoring immediately after launch

The first days after a migration are about observation, not panic.

From experience, some fluctuation is normal.

You should monitor:

Indexing in Search Console
Coverage errors
Crawl activity
Major traffic changes
Server errors

Do not overreact to daily movement. Look for patterns.

using Search Console correctly after migration

Search Console is your primary diagnostic tool.

From experience, you should:

Submit updated sitemaps
Monitor indexing status
Watch excluded URLs
Track impressions and clicks
Compare pre and post migration periods

Search Console data lags slightly. Patience is required.

understanding temporary ranking drops

Temporary drops are common.

From experience, Google needs time to reprocess signals.

As long as redirects are correct and content relevance is preserved, rankings often recover over weeks.

Permanent drops usually indicate structural or relevance issues.

diagnosing problems when recovery does not happen

If recovery stalls, structured diagnosis is needed.

From experience, common causes include:

Missing or incorrect redirects
Changed page intent
Lost internal linking
Weakened content depth
Technical crawl barriers

Random fixes rarely help. Methodical analysis does.

content consolidation during migrations

Migrations are often an opportunity to clean up content.

From experience, consolidation must be done carefully.

Merging similar pages can improve clarity, but only if redirects are precise and content intent is preserved.

Deleting content without considering backlinks or historical value is risky.

internal linking after migration

Internal linking often breaks silently.

From experience, many migrated sites retain old internal links pointing to redirected URLs.

This weakens signal flow.

Updating internal links to point directly to final URLs improves clarity and crawl efficiency.

handling backlinks and external signals

Backlinks are one of the hardest things to migrate.

From experience, you cannot control external links easily, but redirects preserve most value.

For critical backlinks, outreach to update links can help, but it is rarely urgent.

Focus on clean redirects first.

migrating ecommerce sites

Ecommerce migrations carry additional risk.

From experience, product URLs, category structure, filters, and faceted navigation all require special attention.

Preserving product intent and category relevance is essential.

Out of stock handling should also be planned to avoid indexation issues.

migrating content heavy sites

Large content sites require prioritisation.

From experience, you cannot fix everything at once.

Focus first on:

High traffic sections
High value categories
Top linked content

Long tail recovery often follows once core sections stabilise.

mobile and performance considerations

Migrations often change performance.

From experience, new designs can introduce heavy scripts or images.

Monitoring Core Web Vitals before and after migration helps identify regressions.

Performance regressions can slow recovery.

analytics and data continuity

Tracking must be in place from day one.

From experience, missing analytics data after a migration makes diagnosis much harder.

Ensure analytics, events, and goals are tested before launch.

Data continuity matters for decision making.

communicating internally during a migration

Migrations affect teams beyond marketing.

From experience, sales, support, and operations should know a migration is happening.

Temporary changes in enquiry patterns should be expected and understood.

Clear communication prevents misinterpretation of short term effects.

timing a migration properly

Timing matters.

From experience, avoid migrating during peak business periods.

Choose a quieter window where temporary fluctuation is less costly.

Seasonality should always be considered.

how long a migration really takes to settle

Most migrations take weeks to stabilise, not days.

From experience, full trust transfer can take one to three months depending on site size and complexity.

Large sites may take longer.

Planning expectations realistically prevents panic.

learning from a migration

Every migration teaches lessons.

From experience, documenting what worked and what did not improves future decisions.

SEO maturity comes from learning, not avoiding change forever.

when to seek expert help

Not every migration needs an agency, but complex ones often do.

From experience, migrations involving large sites, rebrands, or structural changes benefit from specialist oversight.

The cost of help is often far less than the cost of recovery from mistakes.

the mindset required for a successful migration

The biggest mindset shift is this.

A migration is not a moment. It is a process.

From planning, through execution, to monitoring and refinement, each stage matters.

SEO success comes from respecting that process.

bringing it all together

Knowing how to migrate a site is about far more than moving files or changing designs.

From experience, successful migrations protect what already works while creating space for improvement.

They are planned carefully, executed calmly, and monitored patiently.

Poor migrations damage trust and visibility. Good migrations strengthen foundations and enable growth.

If you treat a site migration as a strategic business project rather than a technical chore, the results are almost always better.