---
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"@id": https://www.twilio.com/docs/api/errors/64021#article
headline: "64021: Pay: Invalid Operation"
url: https://www.twilio.com/docs/api/errors/64021
inLanguage: en
dateModified: 2026-03-11T22:03:37.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 64021: Pay: Invalid Operation

Log Type: APPLICATION

Log Level: ERROR

## Description

A 64021 Error is an indication invalid operation was provided.

### Possible causes

* Start operation on already started Pay session

### Possible solutions

* Make sure to use a valid operation