Your Ultimate Website Relaunch Checklist: Keep GA4 & GTM Tracking Alive (Without Losing Your Mind)

Redesigning your website is a big move - equal parts exciting and overwhelming. Think of it like a cross-country road trip: you need a solid plan to avoid detours and dead ends. But instead of snacks and spare tires, we’re talking analytics and tags.

Ketul Dave

Implementation Specialist

Ketul is a digital wizard who turns complex problems into elegant solutions. Beyond coding, he conquers virtual realms, explores new destinations, and creates boundary-pushing experiences. Ketul is fluent in languages like JavaScript, Python, and PHP, and is a master of GA4 and GTM, seamlessly blending tech prowess with analytics finesse.

Our team has seen what happens when tracking gets left behind during a relaunch. Let’s make sure your GA4 and GTM stay aligned and your data keeps flowing post-launch.

Here’s your practical, no-nonsense guide to a seamless analytics transition.

GTM Container: Reuse or Rebuild?

Same Container ID?
- If your site structure is mostly unchanged, keep the same GTM container. Familiarity = fewer headaches.
- BUT if the new site is a total overhaul (new CMS, rebuilt data layer, or a checkout flow that looks like it’s from 2030), start fresh. Rebuild the container. Yes, it’s work, but better than duct-taping old code to new logic.
Triggers & Variables:
- Audit every trigger tied to URLs, buttons, forms, or DOM elements. That “Free Trial” button with class .btn-cta? If it’s now .fancy-cta-2024, your tag won’t fire.
- Check custom JavaScript variables. Did developers rename userSubscriptionType to userTier? Update it, or your data’s toast.

GA4 Config: Don’t Let Settings Go Rogue

Measurement ID: Confirm it’s firing via GTM on the new site. No ID = no data. Cue existential crisis.
Enhanced Measurement: Scroll tracking, file downloads, outbound links—did the new site accidentally disable these? Peek under the hood.
Internal Traffic Filters: If your dev team’s IP changed, or staging moved to a new domain (e.g., dev.yoursite.com → beta.yoursite.com), update these. Otherwise, your team’s testing clicks will inflate traffic numbers.

Data Layer: The Invisible Puppeteer

If your new site has a rebuilt checkout, forms, or dynamic content, the data layer might push events with new parameters. Example: Is transaction_id now order_id? Time to edit GTM tags.
Pro Tip: Beg developers for a data layer spec doc. Bribe them with pizza. 🍕

Ecommerce Tracking: Show Me the Money

For GA4 ecommerce (standard or enhanced):
- Confirm the purchase event fires with all parameters (e.g., value, currency, items array).
- Check if the data layer structure matches what GTM expects. If the old site used productPrice and the new one uses price, your revenue report will look like a desert.

Cross-Domain Tracking: Avoid User Amnesia

If your checkout lives on shop.yoursite.com and the new site uses checkout.yoursite.com:
- Update GA4’s domain list in your tag settings.
- Add the new domain to GA4’s Referral Exclusion List (Admin → Data Streams → More Tagging Settings). Otherwise, GA4 treats the checkout as a bounce. Poof! User journey gone.

Consent & Privacy: Don’t Get Sued

Test your cookie banner or consent tool (e.g., Cookiebot, OneTrust). If it’s broken, you’re tracking users without consent. GDPR fines = not a vibe.
Using Consent Mode or tag blocking in GTM? Ensure the logic still works. No one wants tags firing before users click “Accept.”

Phase 2: Launch Day (Controlled Chaos)

Debug Like Your Job Depends on It (Because It Does)

GTM Preview Mode + GA4 DebugView: Test every. Single. Tag. Watch events roll in live. No purchase events? Panic (but calmly).
User Flow Smackdown: Physically click through:
Homepage → Product Page → Add to Cart → Checkout → Thank You.
If you’re not sweating by the end, you did it right.

Real-Time Reports: Your New Obsession

Stare at GA4’s Realtime report like it’s a Netflix thriller. See traffic? Good. Spot a referral from sketchy-website.ru? Investigate. Now.

Redirects & UTMs: The Silent Killers

Test old campaign URLs (e.g., ?utm_source=spring_sale). If redirects drop parameters, your traffic will attribute to direct/none. RIP marketing ROI.

Phase 3: Post-Launch Paranoia (Embrace the Anxiety)

Monitor Like a Hawk for 7–14 Days

Compare post-launch metrics to pre-launch baselines. Traffic down 40%? Could be tracking… or maybe your CEO forgot to announce the launch.
Set up GA4 custom alerts for sudden drops in conversions or traffic.

CSI: Data Discrepancies Edition

Missing events? Use GA4’s DebugView and GTM’s Workspace to see where tags broke.
Check JavaScript errors in Chrome DevTools. “Uncaught TypeError” = your new nemesis.

Clean Up Tag Graveyard

Delete tags for retired features (e.g., that newsletter popup you finally killed). No one needs phantom tags hogging bandwidth.

Bonus: Tips

Rebuild vs. Reuse Containers: If the site’s DNA changed, rebuild. Laziness = chaos.
Internal Traffic Filters: Forgot this once. My top traffic source was 127.0.0.1. Don’t be me.
Custom Events: That “Video Play” tag using .vimeo-player? If it’s now .awesome-vid, update it.

Final Wisdom (From Someone Who’s Cried Over Broken Tags)

Document everything. Screenshot settings. Write down why you renamed that trigger. When your boss asks why conversions dropped, you’ll have receipts—not panic sweats.
Celebrate small wins. Fixed a broken tag? Found a missing transaction_id? Do a little dance. You’ve earned it.
Test in incognito mode to avoid cookie conflicts.
Use Google Tag Assistant to scan for missing tags.
If a metric looks weird, ask: Is this a tracking issue or a real problem?

Launching a new website is chaos, but with this checklist, you’ll survive (and maybe even enjoy it). And hey, if it all goes sideways? At least the site looks amazing.

Need a hug, a GA4 audit, or meme to cope? We’re here.

TL;DR: Test everything, assume nothing, and keep the coffee flowing. You’ve got this!**

Below is a summary of key areas where the checklist could be strengthened, followed by concrete suggestions and the rationale for each. These updates reflect recent GA4/GTM platform changes in 2025, server‑side tagging best practices, consent‑mode requirements, and API deprecations.

Summary of Recommended Updates

First‑Party Mode & gtag.js – Leverage Google’s new first‑party tag deployment option to improve tag durability.
Data API & “(not set)” Change – Account for the Data API returning blanks instead of “(not set)” from March 2025 onward.
Server‑Side Tagging – Add a dedicated phase for setting up and validating server‑side containers (web → server).
Consent Mode V2 – Include explicit “must‑have” steps for Consent Mode V2 in EU/EEA markets.
Recommended Events & Ecommerce Enhancements – Surface the new GA4 recommended events and enhanced ecommerce parameters.
API Deprecations & Key Events – Update any API references to use the new KeyEvent resource in the Admin API.
Cost Data Import – Call out new required fields for cost‑data import in GA4.
Region‑Specific Behavior – Highlight GTM’s region‑specific settings for advanced consent and privacy controls.

1. First‑Party Mode & gtag.js

Add a “First‑Party Mode” subsection under Pre‑Launch Prep:
Why? Google now recommends deploying the global site tag or GTM in first‑party mode for more reliable cookie handling and fewer ad‑blocker conflicts citeturn0search15.
Suggest toggling on first‑party mode in the GTM Admin UI (or gtag.js snippet) and verifying via DevTools that the _gac_ cookies are set with same‑site Lax by default.

2. Data API & “(not set)” Change

Note: “(not set)” will be replaced by blank fields in GA4’s Data API from March 2025 onward citeturn0search22.
- Checklist item: Validate any downstream reporting scripts or BI tools expect empty strings instead of “(not set)”.
- Reason: Prevent surprise data‑quality issues when Data API queries start returning null/empty values.

3. Server‑Side Tagging

Insert a new “Phase 1.5: Server‑Side Tagging Setup” between Data Layer and Ecommerce Tracking.
1. Create & configure a Server container (custom domain, TLS) citeturn0search7.
2. Define Clients & Tag routing (e.g., GA4 Config → server endpoint).
3. Test end‑to‑end: ensure web container events reach server container and onward to GA4 without errors.
Why? Server‑side tagging improves data control, reduces ad‑blocker loss, and offloads vendor scripts citeturn0search2.

4. Consent Mode V2

Explicit “Consent Mode V2” step in Pre‑Launch Prep under Consent & Privacy:
- “Implement Google Consent Mode V2, configure default behaviors for ad_storage & analytics_storage per EU/EEA regulations” citeturn0search9turn0search4.
Reason: As of April 2025, EU/EEA publishers are required to support Consent Mode V2 or fall foul of GDPR/PECR guidance.

5. Recommended Events & Ecommerce Enhancements

Under Enhanced Measurement & Ecommerce Tracking, add:
- New GA4 recommended events (e.g., view_promotion, select_promotion, generate_lead) citeturn0search19.
- Enhanced ecommerce param checks: verify item_list_name, promotion_id are populating correctly.
Why? Capturing the full suite of recommended events unlocks richer GA4 reports and predictive insights.

6. API Deprecations & Key Events

Update any Admin API to use KeyEvent instead of the now‑deprecated ConversionEvent resource citeturn0search14.
Checklist: Review any custom scripts or CI pipelines calling the Admin API and refactor accordingly.

7. Cost Data Import

Under Phase 3 Post‑Launch Paranoia → CSI, add:
“Validate cost‑data imports now require source, medium, and date fields in GA4 Data Import” citeturn0search17.
Reason: Pending enforcement since February 3, 2025; missing fields will cause import failures.

8. Region‑Specific Behavior

In Consent & Privacy, note:
“Enable GTM region‑specific settings to tailor tag behavior (advanced consent, data redaction) based on user location” citeturn0search20.
Why? Helps automate compliance across multi‑jurisdictional properties and ensures privacy rules fire correctly.

Implementing these updates will keep your relaunch checklist fully aligned with the latest GA4/GTM platform capabilities and compliance requirements.

At Napkyn, we help organizations assess readiness, build scalable GTM infrastructures, and navigate privacy requirements with confidence. Talk to our Implementation Experts today.

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