---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/51120#article
headline: "51120: Twilsock: Token is not valid yet"
url: https://www.twilio.com/docs/api/errors/51120
inLanguage: en
dateModified: 2026-06-09T11:00:42.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 51120: Twilsock: Token is not valid yet

Log Level: ERROR

## Description

This error occurs when a Twilsock connection tries to authenticate with an Access Token before the token's validity window begins. Twilio Access Tokens can include an optional `nbf` claim that defines the earliest time the token is accepted.

### Possible causes

* The token's `nbf` claim is set to a future Unix timestamp.
* The system clock on the token-issuing host is ahead or behind the validating system, which makes the token appear too early for use.
* Your client attempts to initialize the SDK immediately with a token that is not yet valid.

### Possible solutions

* Remove the `nbf` claim if you do not need a delayed start time.
* If you use `nbf`, set it to the current epoch time so the token is valid as soon as your client receives it.
* Verify the system time on the machine that generates the token and correct any clock drift before issuing new tokens.
* Generate a fresh Access Token closer to the time of use.
* Create and sign Access Tokens with a Twilio helper library to ensure the token structure and claims are generated correctly.
* For long-lived client sessions, renew tokens before they expire by handling your SDK's token refresh events.

#### Additional resources

* [Access Tokens](/docs/iam/access-tokens)
* [Create Access Tokens for Conversations](/docs/conversations/create-tokens)
* [Issuing Sync Tokens](/docs/sync/identity-and-access-tokens)