---
title: CXErrorCodeNotificationServiceExtensionError.Code.unknown
framework: callkit
role: symbol
role_heading: Case
path: callkit/cxerrorcodenotificationserviceextensionerror-swift.struct/code/unknown
---

# CXErrorCodeNotificationServiceExtensionError.Code.unknown

An error that occurs when there is an unknown problem.

## Declaration

```swift
case unknown
```

## See Also

### Error Codes

- [CXErrorCodeNotificationServiceExtensionError.Code.invalidClientProcess](callkit/cxerrorcodenotificationserviceextensionerror-swift.struct/code/invalidclientprocess.md)
- [CXErrorCodeNotificationServiceExtensionError.Code.missingNotificationFilteringEntitlement](callkit/cxerrorcodenotificationserviceextensionerror-swift.struct/code/missingnotificationfilteringentitlement.md)