---
title: Adopting Swift Error Constants
framework: system
role: article
role_heading: Article
path: system/adopting-errno
---

# Adopting Swift Error Constants

Migrate existing C code to Swift, using the error constants provided by the System module.

## Overview

Overview The C error constants map to Swift as follows: E2BIG ⟶ argListTooLong EACCES ⟶ permissionDenied EADDRINUSE ⟶ addressInUse EADDRNOTAVAIL ⟶ addressNotAvailable EAFNOSUPPORT ⟶ addressFamilyNotSupported EAGAIN ⟶ resourceTemporarilyUnavailable EALREADY ⟶ alreadyInProcess EAUTH ⟶ authenticationError EBADARCH ⟶ badCPUType EBADEXEC ⟶ badExecutable EBADF ⟶ badFileDescriptor EBADMACHO ⟶ malformedMachO EBADMSG ⟶ badMessage EBADRPC ⟶ rpcUnsuccessful EBUSY ⟶ resourceBusy ECANCELED ⟶ canceled ECHILD ⟶ noChildProcess ECONNABORTED ⟶ connectionAbort ECONNREFUSED ⟶ connectionRefused ECONNRESET ⟶ connectionReset EDEADLK ⟶ deadlock EDESTADDRREQ ⟶ addressRequired EDEVERR ⟶ deviceError EDOM ⟶ outOfDomain EDQUOT ⟶ diskQuotaExceeded EEXIST ⟶ fileExists EFAULT ⟶ badAddress EFBIG ⟶ fileTooLarge EFTYPE ⟶ badFileTypeOrFormat EHOSTDOWN ⟶ hostIsDown EHOSTUNREACH ⟶ noRouteToHost EIDRM ⟶ identifierRemoved EILSEQ ⟶ illegalByteSequence EINPROGRESS ⟶ nowInProgress EINTR ⟶ interrupted EINVAL ⟶ invalidArgument EIO ⟶ ioError EISCONN ⟶ socketIsConnected EISDIR ⟶ isDirectory ELAST ⟶ lastErrnoValue ELOOP ⟶ tooManySymbolicLinkLevels EMFILE ⟶ tooManyOpenFiles EMLINK ⟶ tooManyLinks EMSGSIZE ⟶ messageTooLong EMULTIHOP ⟶ multiHop ENAMETOOLONG ⟶ fileNameTooLong ENEEDAUTH ⟶ needAuthenticator ENETDOWN ⟶ networkDown ENETRESET ⟶ networkReset ENETUNREACH ⟶ networkUnreachable ENFILE ⟶ tooManyOpenFilesInSystem ENOATTR ⟶ attributeNotFound ENOBUFS ⟶ noBufferSpace ENODATA ⟶ noData ENODEV ⟶ operationNotSupportedByDevice ENOENT ⟶ noSuchFileOrDirectory ENOEXEC ⟶ execFormatError ENOLCK ⟶ noLocks ENOLINK ⟶ noLink ENOMEM ⟶ noMemory ENOMSG ⟶ noMessage ENOPOLICY ⟶ noSuchPolicy ENOPROTOOPT ⟶ protocolNotAvailable ENOSPC ⟶ noSpace ENOSR ⟶ noStreamResources ENOSTR ⟶ notStream ENOSYS ⟶ noFunction ENOTBLK ⟶ notBlockDevice ENOTCONN ⟶ socketNotConnected ENOTDIR ⟶ notDirectory ENOTEMPTY ⟶ directoryNotEmpty ENOTRECOVERABLE ⟶ notRecoverable ENOTSOCK ⟶ notSocket ENOTSUP ⟶ notSupported ENOTTY ⟶ inappropriateIOCTLForDevice ENXIO ⟶ noSuchAddressOrDevice EOPNOTSUPP ⟶ notSupportedOnSocket EOVERFLOW ⟶ overflow EOWNERDEAD ⟶ previousOwnerDied EPERM ⟶ notPermitted EPFNOSUPPORT ⟶ protocolFamilyNotSupported EPIPE ⟶ brokenPipe EPROCLIM ⟶ tooManyProcesses EPROCUNAVAIL ⟶ rpcProcedureUnavailable EPROGMISMATCH ⟶ rpcProgramVersionMismatch EPROGUNAVAIL ⟶ rpcProgramUnavailable EPROTONOSUPPORT ⟶ protocolNotSupported EPROTOTYPE ⟶ protocolWrongTypeForSocket EPROTO ⟶ protocolError EPWROFF ⟶ devicePowerIsOff EQFULL ⟶ outputQueueFull ERANGE ⟶ outOfRange EREMOTE ⟶ tooManyRemoteLevels EROFS ⟶ readOnlyFileSystem ERPCMISMATCH ⟶ rpcVersionMismatch ESHLIBVERS ⟶ sharedLibraryVersionMismatch ESHUTDOWN ⟶ socketShutdown ESOCKTNOSUPPORT ⟶ socketTypeNotSupported ESPIPE ⟶ illegalSeek ESRCH ⟶ noSuchProcess ESTALE ⟶ staleNFSFileHandle ETIMEDOUT ⟶ timedOut ETIME ⟶ timeout ETOOMANYREFS ⟶ tooManyReferences ETXTBSY ⟶ textFileBusy EUSERS ⟶ tooManyUsers EWOULDBLOCK ⟶ wouldBlock EXDEV ⟶ improperLink

## See Also

### Adopting System

- [Adopting Swift File Operations](system/adopting-file-operations.md)
- [Adopting Swift File Options](system/adopting-file-options.md)