GA4 problems and how to fix them
GA4 does not usually break loudly. It reports a number that is wrong in a way that looks plausible, and you find out weeks later when someone asks why two systems disagree. Each guide below covers one specific failure, how to confirm it is happening to you, and what to change.
16 guides
Traffic that is not real
Inflated sessions from bots and referral spam, and the traffic drops that follow when you finally filter them.
- GA4 Bot and Spam Traffic: How to Identify and Filter ItHow to identify bot and spam traffic in GA4, why filtering cannot close the gap, and what to do instead: the signals bots control, the two filters worth running, and moving your decision metrics below an act a bot has no reason to perform.
- GA4 Traffic Dropped Suddenly? Here's a Systematic Diagnosis GuideStep-by-step guide to diagnosing sudden GA4 traffic drops, covering tracking breaks, consent mode changes, algorithm updates, bot filtering changes, and a recovery playbook.
- Ad Blockers and Analytics: How Much Traffic You LoseAd blockers block analytics scripts, not just ads, hiding 15-30% of visitors from GA4 on a typical site. Why the loss is selective rather than merely large, what first-party and server-side collection actually recover, and how to size your own gap first.
Attribution that does not add up
Where (not set) comes from, why Ads and GA4 disagree, and how to get campaign data you can defend.
- GA4 (not set) in Source/Medium: Causes and FixesGA4 shows (not set) in source/medium when it receives the hit but cannot classify the traffic. The six causes, the hour-long sequence that names yours, and what to do about the three that have no fix.
- Why Google Ads Shows 200 Clicks But GA4 Records Only 10 (And How to Fix It)Deep dive into why Google Ads clicks never match GA4 sessions, covering consent mode, redirect chains, ad blockers, attribution windows, and bot clicks with a diagnostic framework.
- How to Import Cost Data From Multiple Ad Platforms Into GA4 (And Why It Breaks)GA4 cost data import process, UTM matching fragility, currency and timezone issues, and alternatives for multi-platform ROAS including data warehouses and attribution platforms.
- Campaign Tracking Best Practices: From UTM Parameters to Revenue AttributionLearn the fundamentals of campaign tracking. Covers UTM parameter strategy, naming conventions, tracking implementation, and connecting campaigns to revenue.
Conversions that go missing
Events that fire in preview and vanish in reports, purchases that never arrive.
- Why GA4 Is Missing Conversions for Certain Events (And How to Recover Them)Why GA4 events fail to count as conversions, covering key event marking, case sensitivity, consent mode filtering, counting methods, the 30-event limit, and prevention setup.
- GA4 Conversions Don't Match Google Ads: Here's Why and What to Do About ItWhy GA4 and Google Ads report different conversion counts: the four mechanisms behind the gap, why consent modelling makes it drift, and which number belongs in which decision.
- GA4 Purchases Show in DebugView But Not in Reports: How to Fix ItWhy GA4 purchase events appear in DebugView and real-time but disappear from standard reports, covering consent mode filtering, malformed parameters, thresholding, and deduplication.
- Tags Fire in GTM Preview But GA4 Doesn't Record Them: A Debugging GuideWhy GTM Preview mode shows tags firing successfully while GA4 reports show no data, covering unpublished containers, consent mode, ad blockers, and a three-stage testing workflow.
- Why Your Analytics Shows Duplicate Events (And How to Fix Double-Counting)Common causes of event duplication in GA4 and GTM, diagnostic techniques, prevention strategies including transaction IDs and server-side firing, and how person-level deduplication works.
Auditing and moving on
Check the whole property in one pass, and what to do if you decide GA4 is not the right tool for the question.
- How to Audit GA4 for Data Accuracy (And What to Do When the Numbers Don't Add Up)A 10-point GA4 accuracy audit checklist covering tag verification, consent mode impact, ad blocker losses, data sampling, and when to supplement GA4 with person-level analytics.
- GA4 Data Thresholds Are Hiding Your Reports: Here's How to Work Around ThemWhy GA4 applies data thresholds that hide report data, how Google Signals triggers them, and 5 workarounds including BigQuery export and first-party analytics alternatives.
- UA to GA4 Migration: What You Lose, What You Gain, and What to Do About ItWhat changed from Universal Analytics to GA4, which historical data cannot be migrated, how to adapt your reporting, and when to supplement GA4 with additional analytics tools.
- Beyond Google Analytics: Why E-commerce Brands Need User-Level TrackingDiscover why GA4 falls short for e-commerce and how person-level tracking helps you reduce cart abandonment, increase LTV, and attribute revenue accurately.
Common questions
- Why does GA4 show more sessions than my server logs?
- Almost always bot and spam traffic that GA4 has not filtered. Known bot filtering only catches declared bots from the IAB list, so anything crawling with a normal user agent still counts as a session.
- What does (not set) mean in source/medium?
- GA4 could not attribute the session to a source. The usual causes are missing UTM parameters, a redirect that strips them, a cross-domain gap, or a session that started before consent was granted.
- Can I fix GA4 or should I replace it?
- Most of these are fixable and worth fixing. Replace it when the question you need answered is about individual people over time, because GA4 models sessions and events rather than persistent identities.