Event Tracking Broken (core event stopped firing), PostHog

Event Tracking Broken (core event stopped firing) for PostHog stores. Tracked live in Vortex IQ Nerve Centre. How to read it, why it matters, and how to act on it.

Metrics type: Key Metrics • Category: Analytics

At a glance

Event Tracking Broken (core event stopped firing) is a Nerve Centre alert tracked from PostHog event data. It fires when a designated core event, for example purchase, add_to_cart, or checkout_started, records zero occurrences for more than an hour. A single core event going silent is a precise, high-confidence sign that instrumentation broke on a specific flow, even when overall event volume still looks healthy. This is the most surgical of the tracking alarms.

What it counts	Alert events raised when a core event’s count stays at zero for more than one hour.
Sample type	Backend API data from PostHog event counts, evaluated against the alert rule on each refresh.
Why it matters	One broken event can hide a whole revenue flow while the rest of your dashboard looks normal. This alert isolates the exact event that stopped.
Reading the value	A non-zero count means a core event went silent. Open the alert to see which event and when it last fired.
Currency	count
Time window	RT
Alert trigger	core event count = 0 for >1h
Sentiment key	ph_alert_tracking_broken
Roles	owner, marketing

Calculation

Calculated automatically from your PostHog data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.

Worked example

A representative reading of Event Tracking Broken (core event stopped firing) for a typical merchant on PostHog. Suppose purchase normally fires 40 to 80 times an hour. After a checkout refactor on 18 Apr 26, the event handler is renamed and purchase records zero for two consecutive hours while pageview and add_to_cart keep flowing. The alert fires. Because only one event went dark, you can go straight to the checkout instrumentation rather than auditing the whole site. Cross-reference Core Events Firing to confirm which events are still healthy. For deeper investigation, use Vortex Mind to trace upstream causes; for natural-language exploration, ask Ask Viq.

Sibling cards merchants should reference together

Card	Why merchants reach for it
ph_core_events_firing	Event Health sibling: the live count of core events still firing.
ph_alert_event_volume_drop	Nerve Centre sibling: broad event volume collapse.
ph_top_events	Event Health sibling: your highest-volume events.
ph_event_volume	Executive sibling: total event volume.
ph_health_score	Executive sibling: overall tracking health score.

Reconciling against the vendor’s own dashboard

Where to look in PostHog’s own dashboard:

In PostHog, open the Activity or live events view and filter to the named core event. If it has not appeared for over an hour, the gap matches the alert. A trend insight on that single event, viewed hourly, makes the silence visible against its normal cadence.

Why the Vortex IQ value may legitimately differ:

Reason	Direction	What to do
Event naming. A rename ships the same action under a new event name; the old name reads zero.	Variable	Check for a renamed event firing in parallel.
Low-traffic hour. A genuinely quiet event may hit zero overnight without being broken.	Variable	Confirm the event normally fires hourly.
Ingestion lag. Brief ingestion delays can show a temporary zero that recovers.	Marginal	Re-check after the next refresh.

Cross-connector reconciliation: complement with sibling cards in the same category for the full diagnostic picture. For divergence investigations, use Vortex Mind.

Known limitations / merchant FAQs

Q: How often does Event Tracking Broken (core event stopped firing) update? The card refreshes on the standard data refresh (typically every 30-60 minutes for live integrations). For real-time signals, force a manual refresh from the dashboard.

Q: Which events count as core? Core events are the ones you designate as business-critical, typically the steps in your primary funnel plus purchase. Configure the set so the alert watches what actually matters to revenue.

Q: It fired but the event is firing again. Why? The event was silent for over an hour and then recovered, often after a deploy was rolled back or a renamed event was restored. The alert records the outage window even after recovery.

Q: Can I customise the alert threshold? Yes, alert thresholds are configurable per profile in the Alert Rules tab. Adjust to match your business baseline rather than relying on the generic default.

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Tracked live in Vortex IQ Nerve Centre

Event Tracking Broken (core event stopped firing) is one of hundreds of KPI pulses Vortex IQ tracks across PostHog and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English.

Start for free or book a demo to see this metric running on your own data.