---
title: AccessoryTransportSession.Error.unknown
framework: accessorytransportextension
role: symbol
role_heading: Case
path: accessorytransportextension/accessorytransportsession/error/unknown
---

# AccessoryTransportSession.Error.unknown

An error that indicates a failure with an unknown cause.

## Declaration

```swift
case unknown
```

## See Also

### Identifying session errors

- [AccessoryTransportSession.Error.invalidated](accessorytransportextension/accessorytransportsession/error/invalidated.md)
- [AccessoryTransportSession.Error.unsupported](accessorytransportextension/accessorytransportsession/error/unsupported.md)