Why is my Google Tag Manager event expecting this `_event` value?

Question

We've set up a Google Tag Manager trigger for successful signups. We've configured it like this:

Trigger type: Other - Custom Event
Event name: Successful Signup
This trigger fires on : Some Custom Events
Fire this trigger when an Event occurs and all of these conditions are true
Event equals successful_signup

We fire the event using custom JavaScript like this:

dataLayer.push({'event': 'successful_signup'})

When we inspect the page, it looks like the event is firing, but it's applying an additional condition that we didn't specify: _event equals Successful Signup.

Why is this extra condition being applied?

Answer 1

The Event Name matters

We thought that the "Event Name" was just a human-readable label, but apparently it actually has to match what is sent by JS. Changing it to match what's sent by JavaScript (dataLayer.push({'event': 'successful_signup'})) got it working.