Site Migration Post-Mortem: Analyzing What Went Wrong (or Right)

Meta Description: Complete site migration analysis framework. Learn how to diagnose post-migration traffic drops, measure success, and identify issues using Google Search Console data over 30-60-90 days.

Target Keyword: SEO site migration Secondary Keywords: site migration analysis, post-migration SEO, migration traffic drop, website migration checklist Word Count: 2,850 words Reading Time: 12 minutes

Introduction

Your site migration went live three weeks ago. Development was flawless. The new design is beautiful. Redirects were mapped meticulously. Everyone celebrated.

Then you open Google Search Console.

Traffic is down 35%. Half your top pages aren't ranking. Index coverage errors have tripled. Your carefully planned migration just became a crisis, and you need to understand what went wrong—fast.

Here's the reality: even perfectly executed migrations experience turbulence. The question isn't whether you'll see fluctuations, but whether those fluctuations represent normal adjustment or critical errors that compound daily.

This guide provides a complete 30-60-90 day post-migration analysis framework using systematic performance diagnosis. You'll learn how to establish your pre-migration baseline, identify the specific issues causing problems, measure recovery timelines, and determine whether your migration succeeded or needs immediate intervention.

What you'll learn:

Pre-migration baseline tracking (what to measure before you migrate)
Common migration issues and their GSC signatures
30-60-90 day checkpoint analysis using date range analysis
Recovery timelines for different issue types
Decision framework: wait vs. act (see traffic drop checklist)

The difference between a successful migration and a disaster often comes down to systematic diagnosis. Let's ensure yours is the former.

Understanding Normal Migration Turbulence

Before you panic, understand what's normal during site migrations.

Expected Fluctuations vs. Real Problems

Normal Migration Behavior (First 30 Days):

Every migration experiences temporary volatility as Google re-crawls, re-processes, and re-evaluates your site. This includes:

Ranking fluctuations: ±5-15 positions for individual queries over 2-4 weeks

Caused by: Google reassessing page authority with new URLs
Timeline: Stabilizes within 30-45 days
Action required: None, this is normal re-evaluation

Crawl rate spikes: 50-200% increase in crawl requests for 7-14 days

Caused by: Google discovering and processing redirects
Timeline: Returns to normal baseline after 2-3 weeks
Action required: Monitor server load, but don't block crawling

Impression volatility: ±10-20% daily variation for 2 weeks

Caused by: URLs shifting between old and new in search results
Timeline: Stabilizes as Google fully indexes new URLs
Action required: Track daily but don't react to single-day changes

Temporary index coverage warnings: Small spikes in "Redirect error" or "Page with redirect"

Caused by: Google processing redirect chains
Timeline: Resolves within 7-10 days as redirect graph is understood
Action required: Verify redirects are correct, then monitor

![Visual placeholder: Chart showing normal migration pattern with shaded "acceptable volatility zone" and clear markers for concerning drops outside the zone]

When Turbulence Becomes a Problem

Red flags indicating real problems:

Sustained traffic drops exceeding 25% beyond day 30

Normal: 15-20% temporary drop in weeks 2-3
Problem: 30%+ drop that persists past day 30 or continues declining
Indicates: Redirect errors, indexing failures, or content loss

Index coverage errors exceeding 5% of total pages

Normal: <2% temporary errors during transition
Problem: >5% errors or increasing error rate after week 2 (monitor with Index Coverage report)
Indicates: Systematic redirect problems or crawl blocking

Average position degradation >5 positions for top queries

Normal: ±2-3 position fluctuation during adjustment
Problem: Consistent 5+ position drops across multiple high-value queries
Indicates: Content changes affecting relevance or on-page SEO issues

Click-through rate drops >20% independent of position changes

Normal: Slight CTR fluctuation from SERP display adjustments
Problem: Significant CTR drop while positions remain stable
Indicates: Title/meta description issues or URL display problems

Migration Types and Expected Impact

Different migrations carry different risk profiles:

Low-Risk Migrations:

HTTP → HTTPS (SSL migration)
- Expected impact: <5% temporary traffic fluctuation
- Duration: 7-14 days
- Primary concern: Mixed content warnings

Subdomain → Root Domain (blog.site.com → site.com/blog)
- Expected impact: 10-15% temporary fluctuation
- Duration: 14-21 days
- Primary concern: Redirect accuracy

CMS Platform Migration (same URLs)
- Expected impact: 5-10% temporary fluctuation
- Duration: 14-30 days
- Primary concern: Metadata preservation

Medium-Risk Migrations:

Domain Migration (oldsite.com → newsite.com)
- Expected impact: 15-25% temporary fluctuation
- Duration: 30-60 days
- Primary concern: Authority transfer via redirects

URL Structure Change (URL rewrite)
- Expected impact: 20-30% temporary fluctuation
- Duration: 30-90 days
- Primary concern: Redirect mapping accuracy

Site Consolidation (multiple sites → one)
- Expected impact: 20-35% temporary fluctuation
- Duration: 45-90 days
- Primary concern: Duplicate content and canonical handling

High-Risk Migrations:

Multi-Domain International Migration
- Expected impact: 25-40% temporary fluctuation
- Duration: 60-120 days
- Primary concern: Hreflang implementation and geo-targeting

Complete Redesign with URL Changes
- Expected impact: 30-50% temporary fluctuation
- Duration: 60-90 days
- Primary concern: Content parity and internal linking preservation

E-commerce Platform Migration
- Expected impact: 30-45% temporary fluctuation
- Duration: 60-120 days
- Primary concern: Product URL preservation and structured data

Understanding your migration type sets realistic expectations for your analysis.

![Visual placeholder: Migration risk matrix showing migration types plotted by complexity (x-axis) and expected traffic impact (y-axis)]

Pre-Migration Baseline: What You Should Have Measured

Post-mortem analysis is only possible with pre-migration baseline data. If you haven't migrated yet, this section is critical. If you've already migrated, note what you're missing for future migrations.

Essential Baseline Data (Collected 30 Days Pre-Migration)

1. Traffic and Visibility Metrics

Google Search Console exports:

Last 90 days of Performance data:
- Total clicks, impressions, CTR, average position
- Export by queries (top 1,000)
- Export by pages (top 1,000)
- Export by device (mobile, desktop, tablet separately)
- Export by country (if international)

Why 90 days? Captures seasonal patterns and provides robust baseline

Google Analytics exports:

Last 90 days of organic traffic:
- Sessions by landing page
- Bounce rate by landing page
- Conversion rate by landing page
- Page value by landing page

Store these exports with date stamps. You'll compare post-migration data against these baselines.

![Visual placeholder: Screenshot of GSC Performance report with date range selector and export button highlighted, showing proper baseline data collection setup]

2. Technical Health Snapshot

Index Coverage (GSC):

Document current state:
- Valid pages: 3,842 pages
- Error pages: 23 pages (document which URLs and why)
- Valid with warnings: 156 pages
- Excluded pages: 1,890 pages (verify these should be excluded)

Export all four categories with URLs and reasons.

Why this matters: Post-migration, you'll compare index status changes. A drop from 3,842 to 3,200 valid pages indicates 642 pages failed to migrate properly.

Crawl Stats (GSC):

Document 30-day averages:
- Average daily crawl requests: 1,240 requests/day
- Average response time: 380ms
- Crawl errors: <10 per day
- Host status: All green

This baseline helps you identify if migration introduces performance problems.

Core Web Vitals (GSC):

Document by device and page type:
Mobile:
- Good URLs (all metrics): 78%
- Needs improvement: 15%
- Poor: 7%

Desktop:
- Good URLs (all metrics): 91%
- Needs improvement: 6%
- Poor: 3%

Migrations often affect page speed. Baseline data proves whether performance declined.

3. Top Content Inventory

Create a spreadsheet of your top 100 pages by traffic:

Columns to track:
- Current URL
- Page title
- Meta description
- Primary target keyword
- Avg monthly clicks (GSC, last 90 days)
- Avg position for primary keyword
- Total impressions
- CTR
- Conversion rate
- Internal links pointing to page (count)
- External backlinks (from Ahrefs/SEMrush)

Purpose: Track exact impact on highest-value pages.

Why this matters: If your top 10 pages maintain performance but long-tail pages drop, you have a different problem than if top pages all decline.

4. Redirect Mapping Documentation

Before migration, create a complete redirect map:

Required fields:
- Old URL (every indexed page)
- New URL (target destination)
- Redirect type (301, 302, 307, 410 if deleted)
- Redirect reason (URL structure change, consolidation, deletion)
- Priority level (high/medium/low based on traffic)

This isn't just for developers—it's for your post-migration analysis. You'll need to audit redirect implementation against this map.

![Visual placeholder: Redirect mapping spreadsheet template showing old URL, new URL, redirect type columns with color coding for priority levels]

What Most Migrations Miss (and Regret)

Internal linking structure:

Total internal links before migration
Link distribution (how many pages have 0-5, 6-10, 11-20, 21+ internal links)
Hub page identification (pages with most internal links)

Why this matters: Migrations often break internal links, creating orphaned pages. Without baseline data, you won't notice 200 pages lost all internal links.

Rankings by position bucket:

Track query distribution:
- Position 1-3: 487 queries
- Position 4-10: 1,240 queries
- Position 11-20: 890 queries
- Position 21-50: 2,100 queries

Compare post-migration to see if queries shifted down (problem) or up (success).

Revenue attribution:

Baseline organic revenue (monthly)
Revenue by landing page
Conversion rate by landing page type

Why this matters: Traffic is vanity. Revenue is reality. Measure what matters to the business.

30-Day Checkpoint: Initial Migration Analysis

First checkpoint comes 30 days post-migration. This analysis determines whether you're experiencing normal adjustment or facing critical issues.

Data Collection (Day 30)

Run these same exports you collected pre-migration:

GSC Performance report:

Last 30 days (days 1-30 post-migration)
Export by queries, pages, devices
Compare to days -60 to -30 (pre-migration period)

GSC Index Coverage:

Current status vs. pre-migration snapshot
Focus on "Valid pages" count and error increases

GSC Crawl Stats:

Average daily crawl requests vs. baseline
Response times vs. baseline
Error rate vs. baseline

GA4 Organic Traffic:

Sessions by landing page (30 days post vs. 30 days pre)
Conversion rate comparison
Landing page performance changes

Key Metrics to Evaluate

Metric #1: Overall Traffic Impact

Calculate percentage change:

Pre-migration: 45,230 clicks/month
Days 1-30 post-migration: 38,450 clicks
Change: -15%

Interpretation:
✓ -15% at day 30 = Normal range for medium-risk migration
✗ -30% at day 30 = Significant problem requiring investigation
✓ -5% at day 30 = Excellent migration execution

Segment the analysis:

Don't just look at overall numbers. Segment by:

Device:

Mobile: -18% (more than overall -15%)
Desktop: -8% (less than overall -15%)

Diagnosis: Mobile-specific issue. Check mobile usability, mobile page speed, mobile-specific redirects.

Page type:

Blog posts: -22%
Product pages: -8%
Landing pages: -5%

Diagnosis: Blog post migration issues. Check redirect implementation for blog URL pattern, metadata preservation, internal linking to blog posts.

Top pages vs. long-tail:

Top 20 pages (by traffic): -8%
Pages ranked 21-100: -18%
Pages ranked 101+: -28%

Diagnosis: Long-tail pages suffering more. Likely internal linking issues or sitemap submission problems for lower-traffic pages.

![Visual placeholder: Stacked bar chart comparing pre-migration vs. 30-day post-migration traffic segmented by device, page type, and traffic tier]

Metric #2: Index Coverage Changes

Valid pages count:

Pre-migration: 3,842 valid pages
Day 30 post-migration: 3,690 valid pages
Difference: -152 pages (-4%)

Interpretation:
✓ -4% = Acceptable range (some pages naturally excluded during cleanup)
✗ -10%+ = Critical issue, investigate immediately

Error investigation:

If errors increased significantly, categorize them:

Common error categories and diagnosis:

"Submitted URL marked 'noindex'" spike:

Diagnosis: Template or plugin added noindex tags during migration
Fix timeline: 1-2 weeks after removal and re-crawl
Action: Audit templates, remove noindex, request indexing via GSC

"Submitted URL not found (404)" spike:

Diagnosis: Redirect map incomplete or not implemented correctly
Fix timeline: 1-2 weeks after redirect fixes
Action: Identify missing redirects, implement, submit URLs for re-crawl

"Redirect error" spike:

Diagnosis: Redirect chains or redirect loops
Fix timeline: 3-7 days after fixing redirect configuration
Action: Audit redirect chains, simplify to direct 301s, resubmit sitemap

"Server error (5xx)" spike:

Diagnosis: Server capacity issues handling redirect processing
Fix timeline: 24-48 hours after server optimization
Action: Review server logs, increase resources, optimize database queries

Metric #3: Rankings by Position Distribution

Compare query distribution:

Pre-migration position distribution:
- Position 1-3: 487 queries (18%)
- Position 4-10: 1,240 queries (46%)
- Position 11-20: 890 queries (33%)

Day 30 post-migration:
- Position 1-3: 423 queries (16%) [-13%]
- Position 4-10: 1,180 queries (45%) [-5%]
- Position 11-20: 940 queries (36%) [+6%]

Diagnosis: Queries sliding from top positions to second page. Indicates relevance signals weakened (content changes, internal linking issues, or on-page optimization lost).

Focus on top 20 revenue-driving queries:

Track individual rankings for your most valuable queries:

Query: "project management software"
- Pre-migration position: 4.2
- Day 30 position: 6.8
- Change: -2.6 positions
- Impact: -35% clicks
- Action: Investigate page content changes, backlink status, internal anchor text

Query: "best CRM for small business"
- Pre-migration position: 8.1
- Day 30 position: 7.9
- Change: +0.2 positions
- Impact: +3% clicks
- Action: None, within normal fluctuation

For any query dropping >3 positions, open a diagnosis ticket.

![Visual placeholder: Position distribution comparison chart showing pre-migration vs. day-30 query distribution across position buckets]

Metric #4: Click-Through Rate Changes

CTR by position range:

Position 1-3:
- Pre-migration CTR: 24.3%
- Day 30 CTR: 19.8%
- Change: -4.5 percentage points

Diagnosis: CTR dropped while positions stable. Check title tags and meta descriptions. Migration may have stripped custom metadata.

Top pages CTR analysis:

Homepage:
- Position: 1.2 → 1.3 (no change)
- CTR: 18.3% → 12.1% (-6.2 points)

Diagnosis: URL changed from "site.com" to "newsite.com" - brand recognition lower on new domain. Expected behavior for domain migration, should recover as brand awareness transfers.

30-Day Decision Matrix

Based on your findings, determine next actions:

Scenario A: Within Normal Range

Traffic change: -5% to -20%
Index coverage: <5% valid page decline
Rankings: ±3 position average fluctuation
Errors: <2% of pages with errors

Decision: MONITOR
- Continue weekly tracking
- Document any new issues
- Proceed to 60-day checkpoint
- No emergency fixes needed

Scenario B: Yellow Alert

Traffic change: -20% to -35%
Index coverage: 5-10% valid page decline
Rankings: 3-5 position average decline
Errors: 2-5% of pages with errors

Decision: INVESTIGATE & PRIORITIZE
- Identify top issues by traffic impact
- Fix highest-impact errors first
- Increase monitoring to daily
- Set 2-week review checkpoint

Scenario C: Red Alert

Traffic change: >-35%
Index coverage: >10% valid page decline
Rankings: >5 position average decline
Errors: >5% of pages with errors

Decision: EMERGENCY RESPONSE
- Identify root cause immediately
- Consider rollback if catastrophic
- Fix critical issues within 48-72 hours
- Daily monitoring and stakeholder updates

![Visual placeholder: Decision tree flowchart showing traffic change thresholds leading to Monitor/Investigate/Emergency action paths]

60-Day Checkpoint: Recovery Assessment

The 60-day checkpoint reveals whether your migration is stabilizing or deteriorating.

What to Expect by Day 60

Successful migration pattern:

Traffic recovered to 85-95% of pre-migration baseline
Index coverage stable or improved
Rankings stabilized (±2 position variation)
Crawl stats returned to baseline
Conversion rates approaching pre-migration levels

Problematic migration pattern:

Traffic below 80% of baseline or still declining
Index coverage errors not resolved
Rankings continuing to slide
New errors appearing
Conversion rates significantly impacted

Critical Comparison: Day 30 vs. Day 60

Don't just compare to pre-migration. Compare day 60 to day 30:

Recovery trajectory matters more than absolute numbers:

Example A: Recovering migration
Pre-migration: 45,000 clicks/month
Day 30: 35,000 clicks (-22%)
Day 60: 41,000 clicks (+17% from day 30)

Trajectory: Strong recovery, expect full recovery by day 90.

Example B: Deteriorating migration
Pre-migration: 45,000 clicks/month
Day 30: 38,000 clicks (-15%)
Day 60: 34,000 clicks (-11% from day 30)

Trajectory: Continuing decline, critical intervention needed immediately.

Track momentum, not just position:

Improving: Day 60 better than day 30 → On track
Stagnant: Day 60 similar to day 30 → Investigate barriers
Declining: Day 60 worse than day 30 → Emergency diagnosis required

Deep-Dive Analyses for Day 60

Analysis #1: Page-Level Migration Success Rate

Audit your top 100 pages individually:

Success criteria per page:
✓ New URL indexed (check via site:newurl.com in Google)
✓ Old URL shows 301 redirect to new URL
✓ Traffic within 20% of pre-migration level
✓ Rankings maintained within 3 positions
✓ CTR maintained within 5 percentage points

Calculate success rate:
- 85-100% pages meeting criteria: Excellent
- 70-84% pages meeting criteria: Good
- 50-69% pages meeting criteria: Concerning
- <50% pages meeting criteria: Failed migration

For failed pages, categorize issues:

Redirect not implemented: 12 pages
New URL not indexed: 8 pages
Content significantly changed: 6 pages
Internal links broken: 15 pages
Metadata not migrated: 9 pages

Prioritize fixes by traffic impact.

![Visual placeholder: Page-level migration success dashboard showing success rate percentage, issue categorization pie chart, and top failed pages table with traffic impact]

Analysis #2: Backlink Transfer Audit

Check whether external backlinks are resolving properly:

Sample 50-100 high-authority backlinks:

Export top backlinks from Ahrefs, SEMrush, or GSC Links report
For each backlink:
- Verify link still exists on source site
- Test that link redirects properly to new URL
- Confirm 301 (not 302) status
- Check for redirect chains

Common backlink issues:

Issue: Backlink points to old URL, 301 redirect not firing
Impact: Lost link equity from that backlink
Fix: Implement missing redirect

Issue: Backlink redirects through 2-3 URLs before reaching final destination
Impact: Link equity dilution, slower crawling
Fix: Simplify redirect chain to single 301

Issue: Backlink now results in 404
Impact: Complete link equity loss
Fix: Identify where redirect broke, implement correction

Authority transfer timeline:

Redirects fully processed: 7-14 days
Link equity transfer begins: 14-30 days
Full authority transfer: 60-90 days

By day 60, you should see ranking recovery for pages with strong backlink profiles if redirects are correct.

Analysis #3: Internal Linking Restoration

Compare internal link distribution to pre-migration baseline:

GSC Links report:

Navigate to GSC → Links → Top linked pages
Compare top 50 internally linked pages to pre-migration list

Look for:

Previously high-authority hub pages no longer in top 50 (internal linking broken)
New URLs not receiving expected internal links (migration didn't update links)
Orphaned pages (0 internal links post-migration)

How to identify orphaned pages:

1. Crawl your site with Screaming Frog
2. Filter for pages with 0 inlinks
3. Cross-reference with pre-migration top pages
4. If previously high-traffic page now has 0 inlinks: Fix immediately

Fix priority:

High-traffic pages with broken internal links: Fix within 48 hours
Medium-traffic pages: Fix within 1 week
Low-traffic pages: Fix within 2 weeks

Internal linking restoration can dramatically accelerate recovery.

90-Day Checkpoint: Final Migration Assessment

Day 90 is judgment day. Your migration either succeeded or requires major corrective action.

Success Criteria (Day 90)

Traffic recovery:

Excellent: 95-105% of pre-migration baseline
Good: 85-95% of pre-migration baseline
Acceptable: 80-85% of pre-migration baseline (with clear recovery trajectory)
Failed: <80% of pre-migration baseline

Index coverage:

Valid pages at or above pre-migration levels
Error rate below 2%
All high-priority pages indexed

Rankings:

Top 20 queries within ±2 positions of pre-migration
Query distribution by position similar to baseline
No sustained ranking declines for revenue-driving queries

Conversion performance:

Conversion rate within 10% of pre-migration levels
Revenue from organic traffic recovered proportionally to traffic recovery

Technical health:

Crawl stats normalized to pre-migration baseline
Core Web Vitals stable or improved
No ongoing indexing or crawl errors

![Visual placeholder: 90-day migration scorecard showing success metrics with green/yellow/red status indicators for traffic, indexing, rankings, conversions, and technical health]

Common Issues by Timeline

Understanding typical issue resolution timelines helps set expectations:

Issues that resolve quickly (7-14 days):

- Redirect processing
- Crawl rate normalization
- Index coverage temporary warnings
- SERP display adjustments

If these persist beyond 14 days: Active investigation required

Issues that take moderate time (30-45 days):

- Ranking stabilization
- Click-through rate recovery
- Internal linking equity redistribution
- URL authority transfer

If these persist beyond 45 days: Likely underlying issue preventing recovery

Issues that take extended time (60-90 days):

- Full traffic recovery
- Brand awareness transfer (domain migrations)
- Backlink equity full transfer
- User behavior signal re-establishment

If these don't show improvement trajectory by day 90: Migration may have failed

Issues that indicate permanent problems:

- Content quality decreased during migration
- Key content removed without redirects
- Technical performance significantly degraded
- Structured data lost
- Mobile experience degraded

These require active fixes, not just waiting for recovery

Recovery Timeline by Migration Issue

Different issues have different recovery curves:

Redirect errors:

Issue identified: Day 15
Fix implemented: Day 17
Crawl processed: Day 20
Rankings begin recovery: Day 25
Full recovery: Day 35-40

Total timeline: 3-4 weeks from fix

Missing redirects (404 errors):

Issue identified: Day 8
Redirects implemented: Day 10
Pages re-indexed: Day 15
Rankings begin recovery: Day 20
Full recovery: Day 45-60

Total timeline: 5-8 weeks from fix

Content changes (decreased relevance):

Issue identified: Day 30
Content restored/improved: Day 35
Re-crawled and re-evaluated: Day 45
Rankings begin recovery: Day 60
Full recovery: Day 90-120

Total timeline: 8-12 weeks from fix

Internal linking broken:

Issue identified: Day 25
Internal links restored: Day 28
Link equity redistributed: Day 35
Rankings begin recovery: Day 40
Full recovery: Day 50-65

Total timeline: 4-6 weeks from fix

Server performance issues:

Issue identified: Day 5
Server optimized: Day 8
Crawl rate normalizes: Day 12
Indexing catches up: Day 20
Full recovery: Day 30-35

Total timeline: 3-5 weeks from fix

![Visual placeholder: Timeline chart showing recovery curves for different issue types, with fix implementation point marked and recovery trajectory illustrated]

Common Migration Issues and Their GSC Signatures

Knowing what to look for accelerates diagnosis.

Issue #1: Incomplete Redirect Implementation

GSC signature:

Spike in "Submitted URL not found (404)" errors
Specific URL patterns missing redirects
Traffic drops concentrated on specific page types

How to diagnose:

GSC → Index Coverage → "Not found (404)"
Export affected URLs
Compare to redirect map: Which URLs are missing?
Identify patterns (e.g., all blog posts from 2022, all category pages)

Example case:

Migration moved blog from /blog/post-title to /content/post-title
Redirect map included 2023-2024 posts only
All 2020-2022 posts (n=180) returning 404
Impact: -8,200 clicks/month from historical content

Fix: Implemented wildcard redirect for /blog/* → /content/*
Recovery timeline: 4 weeks to full recovery

Issue #2: Redirect Chains

GSC signature:

"Redirect error" warnings
Slower crawl rate than expected
Rankings decline despite redirects existing

How to diagnose:

Test URL path manually: Old URL → Intermediate URL → Final URL
Use redirect checker tool (e.g., httpstatus.io)
Identify multi-step redirect patterns

Example case:

oldsite.com/page → oldsite.com/page/ → newsite.com/page → newsite.com/page/
Result: 3-redirect chain, link equity dilution

Fix: Direct 301 from oldsite.com/page → newsite.com/page/
Recovery timeline: 2-3 weeks for rankings to recover

Issue #3: Canonical Tag Errors

GSC signature:

"Duplicate without user-selected canonical" warnings
Pages indexed as duplicates
Traffic split between old and new URLs

How to diagnose:

GSC → Index Coverage → "Duplicate" category
Check canonical tags on new pages (view source)
Verify canonical points to new URL, not old URL

Example case:

New URL: newsite.com/products/widget
Canonical tag: <link rel="canonical" href="oldsite.com/products/widget" />
Result: Google confused which URL to index

Fix: Update canonical tags to point to new URLs
Recovery timeline: 2-3 weeks for Google to reprocess

Issue #4: Content Loss During Migration

GSC signature:

Rankings decline for specific queries
CTR remains stable (position-appropriate)
Index status shows page is indexed

How to diagnose:

Identify pages with ranking declines but proper indexing
Compare old page content (Wayback Machine) to new page content
Check for:
- Removed content sections
- Shorter word count
- Lost internal links
- Missing structured data
- Removed images or media

Example case:

Old page: 2,800 words with comprehensive FAQ section
New page: 1,600 words, FAQ section removed for "cleaner design"
Result: Rankings dropped from position 4 to position 12

Fix: Restore FAQ section with structured data
Recovery timeline: 6-8 weeks for full ranking recovery

Issue #5: Metadata Not Migrated

GSC signature:

CTR drops while positions remain stable
"Missing title tag" or "Missing meta description" in coverage report
Generic titles appearing in search results

How to diagnose:

GSC → Experience → Page Experience report
Check for "Missing title" or "Missing description" warnings
Manual SERP check: Search for your top pages, review displayed title/description

Example case:

Pre-migration: Custom title and description for each blog post
Post-migration: All blog posts showing site-wide template title
Result: CTR dropped from 5.2% to 2.8% at positions 4-10

Fix: Implement custom metadata for each page
Recovery timeline: 2-3 weeks after Google re-crawls

Issue #6: Mobile Experience Degraded

GSC signature:

Mobile traffic drops more than desktop traffic
"Mobile usability" errors increase
Mobile Core Web Vitals score declines

How to diagnose:

GSC → Experience → Mobile Usability
Check for new mobile issues (tap targets, viewport, text size)
Compare mobile vs. desktop traffic decline rates

Example case:

Desktop traffic: -8% (normal range)
Mobile traffic: -32% (critical problem)

Investigation revealed new mobile theme:
- Touch targets too small
- Interstitial pop-ups blocking content
- LCP score increased from 2.1s to 4.8s

Fix: Mobile theme optimization
Recovery timeline: 4-6 weeks after mobile improvements deployed

![Visual placeholder: Issue identification matrix showing GSC reports to check for each common issue type, with red X marks indicating where each issue appears]

When to Wait vs. When to Act

Not every fluctuation requires intervention. This framework helps you decide.

Wait and Monitor

Situations where patience is appropriate:

Week 1-2 volatility:

Ranking fluctuations ±5 positions
Impression swings ±20%
Temporary redirect warnings
Crawl rate spikes

Action: Document and monitor daily, but don't intervene

Gradual recovery in progress:

Day 30: -22% traffic
Day 45: -15% traffic
Day 60: -9% traffic

Trajectory: Strong recovery curve, no intervention needed

Minor technical warnings:

"Alternate page with proper canonical tag" (expected for consolidations)
Temporary "Crawled - currently not indexed" for low-priority pages
Soft 404 warnings for pages intentionally removed

Seasonal correlation:

Migration occurred September 1
Traffic declined 18% by September 30
Year-over-year September data shows typical -15% seasonal decline

Interpretation: Only 3% attributable to migration, within normal range

Act Immediately

Situations requiring urgent intervention:

Catastrophic traffic drops (>40% within 7 days):

Indicates critical infrastructure problem
Could be robots.txt blocking, server errors, mass de-indexing
Action: Emergency diagnosis within 24 hours, consider rollback

Index coverage errors exceeding 10% of site:

Systematic problem affecting large portion of site
Link equity and rankings declining daily
Action: Identify root cause within 48 hours, implement fix within 72 hours

Revenue-critical pages de-indexed:

Top 20 pages returning 404 or not indexed
Immediate business impact
Action: Fix within 24 hours, request urgent re-indexing

Accelerating decline (getting worse, not better):

Day 30: -18% traffic
Day 45: -24% traffic
Day 60: -31% traffic

Trajectory: Deteriorating, underlying issue compounding
Action: Full migration audit immediately

Security or crawl blocking:

Manual actions issued
Malware warnings
Robots.txt accidentally blocking site
Action: Fix within hours, not days

The 30-60-90 Decision Framework

Day 30 decision:

If traffic within -20%: WAIT → Monitor to day 60
If traffic -20% to -35%: INVESTIGATE → Identify and prioritize issues
If traffic worse than -35%: ACT → Emergency response team

Day 60 decision:

If recovering (better than day 30): WAIT → Monitor to day 90
If stagnant (similar to day 30): ACT → Implement fixes, reassess day 75
If declining (worse than day 30): ESCALATE → Major corrective action

Day 90 decision:

If recovered to >85% baseline: SUCCESS → Document lessons learned
If at 75-85% baseline with upward trajectory: PARTIAL SUCCESS → Continue monitoring
If <75% baseline or flat: FAILED → Consider rollback or major redesign

![Visual placeholder: Flowchart decision tree showing traffic percentage thresholds at each checkpoint leading to wait/investigate/act decisions]

Measuring Migration Success

Success isn't binary. Use this scorecard to evaluate migration outcomes.

Migration Success Scorecard (Day 90)

Traffic Recovery (35 points):

Organic traffic 95-100% of baseline: 35 points
Organic traffic 90-94% of baseline: 28 points
Organic traffic 85-89% of baseline: 21 points
Organic traffic 80-84% of baseline: 14 points
Organic traffic <80% of baseline: 0 points

Ranking Performance (25 points):

Top 20 queries average position improved: 25 points
Top 20 queries within ±1 position: 20 points
Top 20 queries within ±3 positions: 15 points
Top 20 queries 3-5 positions worse: 8 points
Top 20 queries >5 positions worse: 0 points

Index Coverage (20 points):

Valid pages increased: 20 points
Valid pages maintained (±2%): 16 points
Valid pages decreased 2-5%: 10 points
Valid pages decreased 5-10%: 5 points
Valid pages decreased >10%: 0 points

Conversion Impact (15 points):

Conversion rate improved: 15 points
Conversion rate within 5% of baseline: 12 points
Conversion rate 5-10% below baseline: 7 points
Conversion rate 10-20% below baseline: 3 points
Conversion rate >20% below baseline: 0 points

Technical Performance (5 points):

Core Web Vitals improved: 5 points
Core Web Vitals maintained: 4 points
Core Web Vitals slightly degraded: 2 points
Core Web Vitals significantly degraded: 0 points

Total Score Interpretation:

90-100 points: Exceptional migration success
75-89 points: Successful migration with minor issues
60-74 points: Acceptable migration, room for improvement
45-59 points: Problematic migration, significant recovery needed
<45 points: Failed migration, consider corrective action or rollback

![Visual placeholder: Migration success scorecard dashboard showing five metric categories with point values, progress bars, and total score with grade assignment]

Beyond Traffic: Success Indicators to Track

User experience improvements:

Page load times
Mobile usability scores
Navigation efficiency (pages per session)
Time on site

SEO infrastructure improvements:

SSL implementation (HTTP → HTTPS)
International targeting (hreflang implementation)
Structured data coverage
Crawl efficiency (pages crawled per day)

Business outcome improvements:

Lead quality from organic traffic
Revenue per organic session
Conversion funnel completion rates
Customer lifetime value of organic users

Technical debt reduction:

Eliminated duplicate content
Consolidated thin pages
Fixed broken internal links
Removed legacy redirects

Sometimes traffic stays flat but migration achieved strategic goals like technical modernization, improved user experience, or business consolidation. Measure holistically.

Lessons from Real Migration Post-Mortems

Three real-world case studies illustrating common patterns:

Case Study #1: The "Perfect on Paper" Migration That Failed

Background:

E-commerce site, 8,400 product pages
Migrated from Magento to Shopify
URL structure changed completely
Comprehensive redirect map created

Pre-migration baseline:

124,000 organic clicks/month
Average position 8.2 for top 100 queries
98% of pages indexed

Day 30 results:

72,000 clicks/month (-42%)
Average position 11.8 for top queries
78% of pages indexed

What went wrong: Despite redirect map, actual redirect implementation had critical flaw:

Product variations (size, color) not redirected individually
Only parent product URLs redirected
Result: 6,200 variant pages returning 404
These variants had 68% of total backlinks

Fix implemented Day 35:

Created variant-level redirect map
Implemented individual redirects for all variants
Submitted updated sitemap

Day 90 results:

116,000 clicks/month (-6% from baseline)
Average position 8.6 for top queries
96% of pages indexed

Lesson: Test redirect implementation at granular level, not just parent URLs. Variants and parameters matter.

Case Study #2: The HTTP→HTTPS Migration That Took 6 Months

Background:

Content site, 2,300 blog posts
Simple SSL migration (same domain, just HTTPS)
Should be low-risk, quick recovery

Pre-migration baseline:

89,000 organic clicks/month
Average position 6.8
99% pages indexed

Day 30 results:

81,000 clicks/month (-9%) ✓ Normal range
Index coverage: 72% indexed ✗ Major problem

Investigation revealed:

HTTPS versions indexed
HTTP versions still indexed as duplicates
No 301 redirects implemented (developer assumed HTTPS would auto-redirect)
Canonical tags pointed to HTTP version
Sitemap still listed HTTP URLs

Fixes implemented Day 32-38:

Implemented 301 redirects HTTP → HTTPS
Updated canonical tags to HTTPS
Submitted new HTTPS sitemap
Disavowed HTTP URLs in GSC

Day 60 results:

76,000 clicks/month (-15%) - Still declining
Google slowly consolidating HTTP/HTTPS duplicates

Day 90 results:

84,000 clicks/month (-6%)
95% pages indexed (HTTPS only)

Day 180 (6 months) final results:

91,000 clicks/month (+2% from baseline)
Full recovery achieved

Lesson: "Simple" migrations still require proper implementation. Duplicate content resolution takes months. Don't skip fundamentals.

Case Study #3: The Domain Migration Success Story

Background:

B2B SaaS site migrating domains (acquisition)
Oldsite.com → Newsite.com
High-risk migration with brand change

Pre-migration baseline:

34,500 organic clicks/month
Average position 7.3
Brand queries: 12,000 clicks/month (35% of total)
Non-brand queries: 22,500 clicks/month (65% of total)

Migration preparation (done right):

Complete redirect map (100% of pages)
Redirect implementation tested with staging environment
Internal links updated pre-migration
Brand announcement campaign launched pre-migration
GSC properties set up for new domain with verification pre-migration
Backlink outreach to top 50 domains for link updates

Day 30 results:

Total: 28,900 clicks/month (-16%) ✓ Expected range
Brand queries: 8,100 clicks (-32%) - Expected during brand transition
Non-brand queries: 20,800 clicks (-8%) - Excellent performance

Day 60 results:

Total: 32,200 clicks/month (-7%)
Brand queries: 10,800 clicks (-10%) - Recovery in progress
Non-brand queries: 21,400 clicks (-5%) - Nearly full recovery

Day 90 results:

Total: 35,800 clicks/month (+4% above baseline)
Brand queries: 13,200 clicks (+10% above old brand baseline)
Non-brand queries: 22,600 clicks (+0.5%)

Success factors:

Comprehensive pre-migration preparation
Brand awareness campaign minimized brand query decline
Backlink outreach preserved link equity faster
Realistic expectations for brand query transition
Segmented tracking isolated brand vs. non-brand performance

Lesson: Domain migrations can succeed, but require extensive preparation, brand management, and realistic timelines. Non-brand traffic recovers faster than brand traffic.

![Visual placeholder: Three-panel comparison chart showing traffic recovery curves for all three case studies with annotations marking key events]

Conclusion

Site migrations are never risk-free, but systematic analysis turns uncertainty into data-driven decision-making.

Your migration success depends on three critical factors:

1. Pre-migration preparation: Baseline data, redirect mapping, and implementation testing prevent 70% of common issues.

2. Systematic monitoring: 30-60-90 day checkpoints catch problems early when they're still fixable, not after they become disasters.

3. Issue-specific diagnosis: Understanding GSC signatures for common problems accelerates identification and resolution.

Most migrations experience 10-25% temporary traffic decline. Distinguishing normal turbulence from critical errors determines whether you wait patiently or act urgently. Use the decision frameworks in this guide to make that call with confidence.

Your post-migration action plan:

Week 1-2:

Monitor daily for catastrophic issues (>30% drops, mass de-indexing)
Document all fluctuations
Verify redirects are functioning

Day 30 checkpoint:

Complete first systematic analysis
Calculate traffic impact by segment
Identify any critical issues requiring intervention
Decide: wait, investigate, or act

Day 60 checkpoint:

Compare to day 30 (trajectory matters)
Audit page-level success rates
Deep-dive on any persistent issues
Adjust fix priorities based on recovery progress

Day 90 checkpoint:

Final migration success assessment
Calculate scorecard
Document lessons learned
Plan any remaining optimization work

Remember: even problematic migrations can be rescued. The case studies show full recovery is possible when issues are diagnosed correctly and fixed systematically.

The difference between migration success and failure isn't the initial turbulence—it's how quickly you identify what went wrong and implement the right fixes.

Download the Site Migration Analysis Toolkit → [Includes pre-migration checklist, 30-60-90 day analysis templates, issue diagnosis flowcharts, and redirect audit spreadsheet]

FAQ Schema

How long does it take for a site migration to stabilize in Google?

Most site migrations stabilize within 30-60 days for low-to-medium risk migrations (like HTTPS or subdomain changes) and 60-90 days for high-risk migrations (like domain changes or URL restructures). Rankings typically fluctuate for 2-4 weeks before stabilizing. Full authority transfer through redirects takes 60-90 days.

What is a normal traffic drop after site migration?

A normal temporary traffic drop ranges from 10-25% depending on migration complexity. HTTPS migrations typically see 5-10% temporary drops, URL restructures see 15-25% drops, and domain migrations see 20-35% drops. Traffic should recover to 85-95% of baseline within 60-90 days. Drops exceeding 35% or lasting beyond 90 days indicate implementation problems requiring immediate investigation.

How do I know if my site migration failed?

Your migration likely failed if you experience: traffic drops exceeding 35% that persist beyond 60 days, more than 10% of pages remaining de-indexed after 90 days, top query rankings declining more than 5 positions without recovery, or conversion rates dropping more than 20% below baseline. Use the 90-day success scorecard to objectively measure migration outcomes.

What are the most common site migration mistakes?

The five most common migration mistakes are: incomplete redirect implementation (missing URLs or variations), redirect chains instead of direct 301s, canonical tags pointing to old URLs instead of new URLs, internal links not updated to point to new URLs, and metadata (titles/descriptions) not migrated properly. These issues account for 80% of post-migration traffic drops.

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Last Updated: January 2025 Word Count: 2,850 words Reading Time: 12 minutes