---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/51004#article
headline: "51004: Client Connection: endpoint_id too long"
url: https://www.twilio.com/docs/api/errors/51004
inLanguage: en
dateModified: 2026-06-09T11:00:42.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 51004: Client Connection: endpoint\_id too long

Log Level: ERROR

## Description

Twilio rejected the client connection because the `endpoint_id` in the Access Token is longer than the supported maximum length. Reduce the length of the `endpoint_id` value and generate a new token before connecting the client.

### Possible causes

* Your application generates an Access Token with an `endpoint_id` value that exceeds the allowed length.
* Your `endpoint_id` includes extra prefixes, identifiers, or concatenated values that make the final string too long.
* Your application builds the `endpoint_id` dynamically and does not validate its length before creating the token.

### Possible solutions

* Shorten the `endpoint_id` value in the Access Token and try the connection again.
* Update your token generation logic to validate the `endpoint_id` length before issuing the token.
* Remove unnecessary dynamic data from the `endpoint_id`, such as long environment names, session values, or repeated prefixes.
* Review your Voice SDK token generation flow to make sure the client identity and connection parameters stay within supported limits.

#### Additional resources

* [Voice SDKs overview](/docs/voice/sdks)
* [Access Tokens](/docs/iam/access-tokens)
* [Programmable Voice documentation](/docs/voice)