# X Activity API event types renamed from PascalCase to dot-separated lowercase

- **Provider:** X (Twitter)
- **Endpoint:** `* /2/activity/**`
- **Effective:** 2026-03-18
- **Severity:** high
- **Change:** enum-added
- **Status:** verified

## What changed

From 2026-03-18 the X Activity API (XAA) uses dot-separated lowercase event_type values such as profile.update.bio instead of PascalCase names such as ProfileBioUpdate. Subscriptions created with, or event handlers that switch on, the old names stop matching.

## What to do

Send the new lowercase names (for example profile.update.bio, follow.follow, post.create) in POST /2/activity/subscriptions and update every filter, switch statement and deserializer that reads event_type from the activity stream or webhook payloads.

## Sources

- Provider notice (2026-03-13): https://docs.x.com/changelog
- https://docs.x.com/x-api/activity/introduction

## Machine-readable

- Advisory: https://github.com/SriVarshini09/shapi-advisories/blob/main/advisories/x-activity-api-pascalcase-event-types-removed.json
- OSV: https://shapi.dev/osv/x-activity-api-pascalcase-event-types-removed.json