---
title: Error Dictionary Keys
framework: cfnetwork
role: collectionGroup
role_heading: API Collection
path: cfnetwork/error-dictionary-keys
---

# Error Dictionary Keys

Networking-related keys that may be available in a CFErrorRef object’s userInfo dictionary.

## Overview

Overview Many network functions return CFErrorRef objects. When the error object’s domain is kCFErrorDomainCFNetwork, you can query the object for additional information. For example: if (CFEqual(CFErrorGetDomain(err), kCFErrorDomainCFNetwork) && CFErrorGetCode(err) == kCFHostErrorUnknown) {       CFDictionaryRef userInfo = CFErrorCopyUserInfo(err);       CFNumberRef number = (CFNumberRef) CFDictionaryGetValue(userInfo, kCFGetAddrInfoFailureKey);       ...       CFRelease(userInfo); }

## Topics

### Constants

- [kCFURLErrorFailingURLErrorKey](cfnetwork/kcfurlerrorfailingurlerrorkey.md)
- [kCFURLErrorFailingURLStringErrorKey](cfnetwork/kcfurlerrorfailingurlstringerrorkey.md)
- [kCFGetAddrInfoFailureKey](cfnetwork/kcfgetaddrinfofailurekey.md)
- [kCFSOCKSStatusCodeKey](cfnetwork/kcfsocksstatuscodekey.md)
- [kCFSOCKSVersionKey](cfnetwork/kcfsocksversionkey.md)
- [kCFSOCKSNegotiationMethodKey](cfnetwork/kcfsocksnegotiationmethodkey.md)
- [kCFDNSServiceFailureKey](cfnetwork/kcfdnsservicefailurekey.md)
- [kCFFTPStatusCodeKey](cfnetwork/kcfftpstatuscodekey.md)

## See Also

### Errors

- [CFNetworkErrors](cfnetwork/cfnetworkerrors.md)
- [Error Domains](cfnetwork/error-domains.md)