---
page_type: error
code: 20429
message: "20429: Too many requests"
level: ERROR
product: Platform
---

## Description

Twilio returns this error when your account exceeds allowed concurrency to Twilio's REST API (HTTP 429 Too Many Requests). Requests that receive 429 responses aren't processed and are safe to retry after backing off.

### Possible Causes

- Excessive concurrent REST API requests from the account, exceeding platform concurrency limits.
- Multiple verification starts initiated in a short period for the same phone number, triggering a concurrency safeguard on Verify endpoints (HTTP 429).
- Built-in Verify attempt limits reached, such as max send attempts or max check attempts, which return HTTP 429.
- Exceeding Verify Service Rate Limits that you configure (for example, per phone number or other keys), enforced when starting verifications.
- Polling verification status above the documented per-minute/hour/day limits.

### Possible Solutions

- Implement retries with exponential backoff; 429 responses are safe to retry.
- Throttle or queue requests to reduce concurrent API calls to Twilio until you remain under concurrency limits.
- For verification flows, avoid repeatedly starting new verifications for the same number; complete the lifecycle by checking the existing verification or allow it to expire before starting another.
- Define and tune Verify Service Rate Limits (for example, per phone number, IP, or session) and pass the appropriate keys when starting verifications.
- Reduce verification status polling to stay within the documented limits.
- Monitor Twilio response headers like Twilio-Concurrent-Requests to understand current load and adjust client behavior.

#### Additional resources

- [API best practices](/docs/usage/rest-api-best-practices)
- [Rate limits and timeouts](/docs/verify/api/rate-limits-and-timeouts)
- [Protect your Verify application with Service Rate Limits](/docs/verify/api/programmable-rate-limits)
- [Service Rate Limits](/docs/verify/api/service-rate-limits)
- [Twilio API response Error 429 "Too Many Requests"](https://help.twilio.com/hc/en-us/articles/360044308153-Twilio-API-response-Error-429-Too-Many-Requests)