---
title: URL session error dictionary keys
framework: foundation
role: collectionGroup
role_heading: API Collection
path: foundation/url-session-error-dictionary-keys
---

# URL session error dictionary keys

Keys used in conjunction with error objects returned by URL sessions and tasks.

## Topics

### User info dictionary keys

- [NSURLSessionDownloadTaskResumeData](foundation/nsurlsessiondownloadtaskresumedata.md)
- [NSURLErrorBackgroundTaskCancelledReasonKey](foundation/nsurlerrorbackgroundtaskcancelledreasonkey.md)

## See Also

### Handling errors

- [Background task cancellation](foundation/background-task-cancellation.md)