How-to · Updated October 11, 2026
Test whether a GA4 event fires with DebugView
Updated October 11, 2026
10 minutes
Connect Tag Assistant to your site, then in GA4 open Admin, Data display, DebugView, pick your device and do the action once. The event should appear within seconds with its parameters. Two for one action means it is counted twice. Reports can take 24 to 48 hours and cannot tell a broken tag from a quiet day.
Before you start
- Access to the GA4 property the site sends to.
- A desktop browser, ideally Chrome with the Tag Assistant extension, with ad blockers you can switch off for the test.
- One action to test, such as a form submission you can recognize later or a click on a booking button.
Turn on debug mode for your browser only
Tag Assistant puts your own browser in debug mode, so nothing on the site changes for visitors.
- Go to tagassistant.google.com and click Add domain.
- Enter your website address, starting with https://, and click Connect. Your site opens with a debug parameter added to the address, which Google says helps DebugView show your events.
- If a cookie banner appears, accept analytics cookies. Google says events do not show in debug mode when consent mode is in place and the visitor has not consented to analytics cookies.
- To test changes that are still unpublished in Tag Manager, click Preview in the Tag Manager workspace instead. It connects the same way and runs the draft container.
Watch the event arrive
DebugView lists each event from your browser as it arrives; click one to see the parameters it carried.
- In GA4, click Admin. Under Data display, click DebugView.
- In the Debug Device menu at the top left, choose your device if more than one is listed.
- On the site, do the action once, and only once.
- Watch the middle column, the Seconds stream, which lists events from the last 60 seconds. Click the event to see its parameters, such as value, currency or a form name.
Read the result
What arrived, and how many times, says which fix comes next.
- Once, with the right name and parameters: the event works. Visitors' events should reach reports, but your own test may not if the property filters out developer traffic (see the drop-downs below).
- Twice for one action: the event is sent twice, either by two tags (often the site builder's own Google tag beside yours) or by one tag on two triggers. Tag Assistant shows which tags fired on the action. GA4 will count every one of these actions twice until one sender is turned off.
- Not at all, while page_view arrives: the tag that sends the event did not fire. Check in Tag Assistant which tags fired on that action, and whether the change was published.
- Nothing at all, not even page_view: first check that this is the property the site sends to, that your device is picked in Debug Device, and that Tag Assistant still shows Connected. If all three hold, the Google tag is not reaching GA4 from this page. Check that the page loads the tag and that an ad blocker or the cookie banner is not stopping it.
Check it worked
A working event usually appears in DebugView within seconds of the action. As a second view, Reports, then Realtime, should list it in the Event count by event name card within a few minutes; Google calls Realtime a best effort service, so a short delay there is not a fault.
Standard reports can take 24 to 48 hours to process, so judge them the next day or later.
Never leave debug mode on for every visitor
Google's alternative to Tag Assistant is a debug_mode parameter set to true in the Google tag, which puts every visitor's events in DebugView. Setting it to false does not turn debug mode off; Google says the parameter has to be removed. Use it only for a short test and take it out afterwards.
The test shows in DebugView but never in reports
A property can have an active data filter that removes developer traffic, meaning events sent in debug mode. Google says an exclude filter's effect is permanent: that data is never processed. It keeps tests out of the numbers, which is the point, so judge your test in DebugView rather than waiting for it in reports.
Tag Assistant will not connect
Ad blockers, a chain of redirects, a cookie banner and a debug parameter that breaks the page can each stop the connection. The steps to clear each are in the Tag Manager preview fix linked below.