Top Mistakes in GA4 (and How to Fix Them)

April 23, 2025
As Google Analytics 4 (GA4) continues to mature—now a few years on from Universal Analytics’ sunset—organisations are still wrestling with common pitfalls that undermine data accuracy, insights, and ROI. In this post, we’ll explore the top mistakes we see in GA4 implementations and share practical fixes to help you get the most from the platform.

1. Neglecting BigQuery Integration

The mistake: You rely solely on the GA4 interface for reporting and skip exporting raw data to BigQuery.

Why it matters: GA4’s UI provides high-level reports, but without BigQuery you lose granular control over data joins, custom analyses, and cross-platform insights.

How to fix it:

  • Enable GA4’s free BigQuery export under Admin → BigQuery Linking.
  • Build scheduled SQL queries in BigQuery to enrich GA4 events with internal CRM or CMS data.
  • Use BI tools (Looker Studio, Data Studio, Tableau) on top of your BigQuery tables for bespoke dashboards.

2. Overlooking Advanced Consent Mode & Modeled Data

The mistake: You stick with default consent settings and ignore Google’s advanced consent-mode features.

Why it matters: Without consent-mode v2, your reports may undercount conversions and sessions when users opt out of tracking, leading to biased insights.

How to fix it:

  • Implement Consent Mode v2 via gtag.js or Tag Manager.
  • Configure ad_storage and analytics_storage settings based on user consent.
  • Leverage GA4’s modelled data capabilities to fill gaps caused by consent restrictions.

3. Failing to Filter Internal Traffic

The mistake: You haven’t configured basic filters like internal IP exclusion, leading to inflated metrics from your own team’s activity.

Why it matters: Internal pageviews, test events, and QA sessions can skew your numbers, making it hard to distinguish real user behaviour.

How to fix it:

  • Under Admin → Data Streams → Tagging Settings → Define Internal Traffic, add your office IP ranges.
  • Create a Data Filter to exclude internal traffic from your reports.
  • Validate by checking real-time reporting from an external network.

4. Mixing App + Web Data Without Proper Partitioning

The mistake: You combine mobile app and website events in one GA4 property without skills to segment them.

Why it matters: App and web events have different user journeys, SDK implementations, and session definitions. Mixing them can muddy attribution and funnel analyses.

How to fix it:

  • Consider using separate GA4 properties for app vs. web—unless you have the expertise to build robust segments.
  • Use User Properties or Event Parameters to label platform = web vs. platform = app.
  • Segment users by platform in your reports or in BigQuery SQL.

5. Not Updating dataLayer to GA4 Schema

The mistake: You’re sending events built for Universal Analytics (UA) via dataLayer without mapping to GA4’s schema.

Why it matters: Parameter names changed between UA and GA4. Sending incorrect keys results in missing custom dimensions, e‑commerce tracking gaps, and ambiguous event names.

How to fix it:

  • Audit your dataLayer pushes against the GA4 recommended naming schema.
  • Rename custom parameters (e.g. event_categorycategory, event_labellabel).
  • Test with GA4’s DebugView and Tag Assistant to confirm dataLayer events arrive correctly.

6. Ignoring Data Retention Settings

The mistake: You leave GA4’s default retention (2 months) on, or set it to the maximum without evaluating your actual needs.

Why it matters: Short retention limits your ability to analyze long-term user behaviors. Excessive retention can raise privacy concerns and storage costs in BigQuery.

How to fix it:

  • Under Admin → Data Settings → Data Retention, choose 14-month retention (or custom) based on your analysis cycle.
  • Regularly review retention policy against compliance requirements (GDPR, CCPA).
  • Archive older data in BigQuery or another data warehouse if you need multi-year history.

7. Misunderstanding Data-Driven Attribution

The mistake: You assume GA4’s default data-driven attribution (DDA) model can be replicated with raw CSV exports or GA4’s API.

Why it matters: GA4’s DDA is based on Google’s proprietary machine-learning pipelines. Simply exporting raw event data won’t give you the same attribution outputs.

How to fix it:

  • Use GA4’s Attribution reports or the Attribution API to pull DDA results.
  • If you need in-house attribution models, build rule-based or custom ML pipelines in BigQuery—but expect differences from GA4’s algorithmic data.

8. Losing Historic Universal Analytics Data

The mistake: You didn’t export your UA data before July 1, 2023, and now you’re missing baseline metrics.

Why it matters: Without UA history, it’s hard to compare year-over-year trends, calculate seasonality, and benchmark performance.

How to fix it:

  • Check if any UA backups exist in Cloud Storage or local archives.
  • If you have UA data in BigQuery (via UA export), import it into your GA4 dataset.
  • Document any gaps and use statistical forecasting to estimate missing periods.

9. Underestimating GA4’s Interface Learning Curve

The mistake: You expect GA4’s new interface to match UA’s layout and terminology—and get frustrated.

Why it matters: GA4 was built to surface insights via BigQuery-powered analysis, not just point‑and-click reporting. Misuse can turn a free tool into a costly data-management headache.

How to fix it:

  • Invest time in GA4’s official training and tutorials (Analytics Academy).
  • Appoint a “GA4 champion” to own BigQuery costs, query optimisation, and data governance.
  • Monitor your BigQuery usage and set budget alerts to prevent unexpected costs.

Conclusion & Next Steps

GA4 brings powerful event-driven analytics and machine-learning attribution to the table—but only if you configure it correctly. Audit your setup by:

  1. Verifying your BigQuery export and querying raw data.
  2. Reviewing consent-mode implementation and data-layer mappings.
  3. Filtering internal traffic and segmenting app vs. web.
  4. Tweaking retention, attribution, and interface training.

By fixing these common mistakes, you’ll unlock GA4’s full potential—ensuring accurate insights, stronger ROI, and a future-proof analytics foundation. Ready to take your GA4 setup to the next level? Contact our team for an in-depth audit and custom training plan.

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