---
title: NSFileManagerUnmountDissentingProcessIdentifierErrorKey
framework: foundation
role: symbol
role_heading: Global Variable
path: foundation/nsfilemanagerunmountdissentingprocessidentifiererrorkey
---

# NSFileManagerUnmountDissentingProcessIdentifierErrorKey

The process identifier of the process that prevented a volume from unmounting.

## Declaration

```swift
let NSFileManagerUnmountDissentingProcessIdentifierErrorKey: String
```

## Discussion

Discussion If unmountVolume(at:options:completionHandler:) fails, the error sent to its completion handler will contain a userInfo dictionary with this string as one of its keys. The value is the process identifier of the process that prevented the unmounting, as an NSNumber.

## See Also

### Unmounting volumes

- [unmountVolume(at:options:completionHandler:)](foundation/filemanager/unmountvolume(at:options:completionhandler:).md)
- [FileManager.UnmountOptions](foundation/filemanager/unmountoptions.md)