---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/60511#article
headline: "60511: SNA Downstream Error"
url: https://www.twilio.com/docs/api/errors/60511
inLanguage: en
dateModified: 2026-06-08T12:04:59.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 60511: SNA Downstream Error

Log Type: TWILIO

Log Level: ERROR

## Description

This error occurs when a Verify request that uses Silent Network Auth fails during downstream SNA processing. Check the Verification Check response for `sna_attempts_error_codes` to confirm that 60511 was returned, then move the user to another verification channel.

### Possible causes

* A required carrier header was missing during the Silent Network Auth flow.
* The phone number used for the verification attempt was invalid.
* The `sna.url` request was invoked on a carrier path that does not support HTTPS for that SNA flow.
* The redirect chain for the `sna.url` invocation was invalid or interrupted before the carrier could complete the check.

### Possible solutions

* Retry the verification with a different Verify channel instead of Silent Network Auth.
* Check `sna_attempts_error_codes` on the Verification Check response and use that result to decide whether to fall back to SMS, voice, WhatsApp, or another supported channel.
* Verify that the destination phone number is valid and formatted in `E.164` before starting a new verification.
* Invoke the one-time `sna.url` from the end user's device over the mobile network and use `POST` for production implementations.
* Allow the SNA redirect flow to complete without rewriting or interrupting the request.
* If you are testing with a browser or Live Test Number, confirm that the device or browser is not forcing HTTPS in a way that breaks the carrier flow.

#### Additional resources

* [Verify Silent Network Auth Overview](/docs/verify/sna)
* [Best Practices for Verify SNA Error Handling](/docs/verify/best-practices-for-verify-sna-error-handling)
* [Verify Channel Selection](/docs/verify/fallback-scenarios)