---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/51127#article
headline: "51127: Twilsock: PNC limit has been"
url: https://www.twilio.com/docs/api/errors/51127
inLanguage: en
dateModified: 2026-06-09T11:00:42.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 51127: Twilsock: PNC limit has been

Log Level: ERROR

## Description

This error occurs when Twilsock rejects a request because your application has exceeded a limit related to push notification registrations or subscriptions. In Conversations, a Binding represents a push notification subscription for a User within a Service instance, and bindings are unique per Service instance, User identity, device, and notification channel.

### Possible causes

* Your application is registering push notification tokens more often than expected for the same user or device.
* Your application is leaving behind stale push notification registrations after a user signs out, reinstalls the app, or switches devices.
* Your client reconnect logic or retry logic is repeatedly creating push notification registrations.
* Your current traffic pattern or number of active push notification bindings is higher than the limit allowed for your account or service.

### Possible solutions

* Register each APNs or FCM token only when needed.
* Unregister old push tokens when a user signs out, when a token rotates, or when the app no longer uses that device.
* Review your client retry and reconnect behavior to make sure it is not repeatedly creating registrations for the same device.
* Review your Conversations implementation for duplicate users, duplicate device registrations, or unnecessary client sessions.
* If the traffic is expected, contact Support to discuss whether your current limit can be adjusted.

#### Additional resources

* [Push Notification Configuration for Conversations](/docs/conversations/push-notification-configuration)
* [Service Binding Resource](/docs/conversations-classic/api/service-binding-resource)
* [Conversations Limits](/docs/conversations/conversations-limits)