---
title: unknown
framework: callkit
role: symbol
role_heading: Type Property
path: callkit/cxerrorcodenotificationserviceextensionerror-swift.struct/unknown
---

# unknown

An error that occurs when there is an unknown problem.

## Declaration

```swift
static var unknown: CXErrorCodeNotificationServiceExtensionError.Code { get }
```

## See Also

### Understanding Error Codes

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