Debugging GA4: DebugView, Realtime, and Tag Assistant Walkthrough

Three Debugging Tools, Different Purposes

Debugging GA4 tracking issues requires different tools depending on what you are investigating. DebugView shows detailed event-level data for a specific device. Realtime shows recent events across all users. Tag Assistant diagnoses tag configuration issues at the GTM/page level.

Tool 1: GA4 DebugView

DebugView is the most granular GA4 debugging tool — it shows every event as it arrives, with all parameters, in real time, for a specific debug session.

How to Enable

• Via browser extension: install Google Tag Assistant (Chrome extension), connect to your site, and enable "Debug" mode. Your browser sends events with debug_mode: 1 parameter.
• Via GTM: add a GA4 Configuration Tag parameter debug_mode with value true
• Via URL: append ?gtm_debug=x to your URL and interact with GTM Preview Mode

What to Look For

• Events appear in the left timeline as you trigger them on your website
• Click any event to see all parameters in the detail panel on the right
• Check: correct event name (not a typo or capitalisation error)
• Check: all required parameters present (transaction_id, value, currency for purchase)
• Check: parameter values are correct (not undefined, not 0 for a £99 purchase)
• Check: events fire exactly once per action (not zero, not twice)

Common DebugView Findings

• purchase event with value = 0 (parameter not passed correctly)
• generate_lead fires on button click instead of form submission confirmation
• page_view fires twice on first load (duplicate tag)

Tool 2: GA4 Realtime Report

Realtime (Reports then Realtime) shows events from all users in the last 30 minutes. Use it for:

• Verifying that a recently deployed change is working across all users
• Confirming events are reaching GA4 after clearing cache on production
• Sanity-checking that session counts look roughly right for the current time of day

Realtime is less precise than DebugView for parameter inspection — it shows event counts and top events but not the full parameter detail of each event. Use DebugView for parameter-level debugging.

Tool 3: Google Tag Assistant

Tag Assistant (tagassistant.google.com) operates at the page/GTM level — it shows you which tags fire on your website, whether they fire correctly, and in what order. Use it for:

• Confirming the GA4 tag fires on all pages (not just the homepage)
• Identifying duplicate GA4 tags (two tags with different Measurement IDs, or the same ID firing twice)
• Verifying the correct GTM container is installed
• Checking for GTM Preview Mode connectivity

Tag Assistant + Connected Sites

Tag Assistant can connect to your site and record a navigation session, then show you all tag fires across multiple pages. This is useful for diagnosing issues that only occur on specific pages or after specific interactions.

Debugging Workflow

1. Start with Tag Assistant: is the correct GA4 tag installed on all pages? Are there any duplicates?
2. Move to DebugView: does the event fire on the correct action? Do all parameters have correct values?
3. Finish with Realtime: is the event reaching GA4 in production (after any GTM publishing or code deployment)?

Summary

GA4 debugging requires three complementary tools: Tag Assistant for page/tag-level diagnosis, DebugView for event and parameter-level inspection, and Realtime for production verification. Use them in sequence — tag installation first, then event parameters, then production confirmation.

See our GA4 Setup & Audit service for tracking diagnostics.

GA4 events not tracking correctly? Contact Adslytics.