Add event_type fails in webhook subscription

Questions
1 
I don't see the  error??


curl https://xxxxxxxxxxxxx \
  -X PUT \
  -H 'Square-Version: 2025-09-24' \
  -H 'Authorization: Bearer xxxxxxxxxxxxx ' \
  -H 'Content-Type: application/json' \
  -d '{
    "subscription": {
      "event_types": [
        "payment.failed"
      ]
    }
  }'

{
  "errors": [
    {
      "category": "INVALID_REQUEST_ERROR",
      "code": "VALUE_EMPTY",
      "detail": "Value for `subscription.event_types` should not be empty.",
      "field": "subscription.event_types"
    }
  ]
}
2

:waving_hand: I’m Square Dev AI, here to help answer your question!
Based on the information you’ve provided, the following documentation will help answer your question:

Additional Documentation

Develop for Japan
Using the REST API
Subscription Plan Checkout

If this documentation helped you find a solution, please check the box indicating that this reply solves the problem.
Otherwise one of our Developer Advocates will provide additional assistance shortly.

3

Currently, a payment.failed webhook event isn’t currently available with Square webhooks. We’re constantly working to improve our features based on feedback like this, so I’ll be sure to share your request to the API product team. :slight_smile:

4

This webhook event is YOUR suggestion from my previous question.
Looks like your AI is both replying and dreaming stuff on your behalf.
LPT: What AI doesn’t know it makes up.

Monitoring event types: The invoice.payment_failed event is the primary event to monitor for payment failures. Additionally, you can monitor the payment.failed event for more granular payment failure details. These events will help ensure you capture all failure cases.

5

This might help – add this prompt to your AI requests
"STRICT REQUIREMENT: Confine your answer exclusively to the official Square Developer documentation (API Reference, SDKs, Guides). Only use the exact object names, field names, API calls, and webhook event names found within the Square ecosystem. Do not cite, infer, or use terminology from non-Square payment processors (e.g., Stripe, PayPal, etc.).

If the request for a feature or event name is ambiguous, or if an essential detail is missing, state what information is needed to answer definitively rather than attempting to infer or guess at an answer."