# Secure Transport Result Codes Recognize result codes specific to the secure transport API. ## Discussion Use the [`SecCopyErrorMessageString(_:_:)`](/documentation/Security/SecCopyErrorMessageString(_:_:)) function to obtain a human readable string corresponding to these status codes. The functions of the [Secure Transport](/documentation/Security/secure-transport) API may also return the general codes listed in [Security Framework Result Codes](/documentation/Security/security-framework-result-codes). Errors in the range of –9819 through –9840 are fatal errors that are detected by the peer. ## Topics ### App Transport Security result codes [`errSSLATSViolation`](/documentation/Security/errSSLATSViolation) An App Transport Security violation occurred. [`errSSLATSMinimumVersionViolation`](/documentation/Security/errSSLATSMinimumVersionViolation) The minimum protocol version isn’t App Transport Security compliant. [`errSSLATSCiphersuiteViolation`](/documentation/Security/errSSLATSCiphersuiteViolation) The selected ciphersuite isn’t App Transport Security compliant. [`errSSLATSMinimumKeySizeViolation`](/documentation/Security/errSSLATSMinimumKeySizeViolation) The peer key size isn’t App Transport Security compliant. [`errSSLATSLeafCertificateHashAlgorithmViolation`](/documentation/Security/errSSLATSLeafCertificateHashAlgorithmViolation) The peer leaf certificate hash algorithm isn’t App Transport Security compliant. [`errSSLATSCertificateHashAlgorithmViolation`](/documentation/Security/errSSLATSCertificateHashAlgorithmViolation) The peer certificate hash algorithm isn’t App Transport Security compliant. [`errSSLATSCertificateTrustViolation`](/documentation/Security/errSSLATSCertificateTrustViolation) The peer certificate wasn’t issued by a trusted peer. ### Certificate issue result codes [`errSSLBadCert`](/documentation/Security/errSSLBadCert) Bad certificate format. [`errSSLBadCertificateStatusResponse`](/documentation/Security/errSSLBadCertificateStatusResponse) Bad OCSP response. [`errSSLCertExpired`](/documentation/Security/errSSLCertExpired) The certificate chain had an expired certificate. [`errSSLCertNotYetValid`](/documentation/Security/errSSLCertNotYetValid) The certificate chain had a certificatethat is not yet valid. [`errSSLCertificateRequired`](/documentation/Security/errSSLCertificateRequired) Certificate required. [`errSSLClientCertRequested`](/documentation/Security/errSSLClientCertRequested) The server has requested a client certificate. [`errSSLHostNameMismatch`](/documentation/Security/errSSLHostNameMismatch) The host name you connected with does not match any of the host names allowed by the certificate. [`errSSLNoRootCert`](/documentation/Security/errSSLNoRootCert) No root certificate for the certificate chain. [`errSSLPeerBadCert`](/documentation/Security/errSSLPeerBadCert) A bad certificate was encountered. [`errSSLPeerCertExpired`](/documentation/Security/errSSLPeerCertExpired) The certificate expired. [`errSSLPeerCertRevoked`](/documentation/Security/errSSLPeerCertRevoked) The certificate was revoked. [`errSSLPeerCertUnknown`](/documentation/Security/errSSLPeerCertUnknown) The certificate is unknown. [`errSSLPeerUnsupportedCert`](/documentation/Security/errSSLPeerUnsupportedCert) An unsupported certificate format was encountered. [`errSSLUnknownRootCert`](/documentation/Security/errSSLUnknownRootCert) Certificate chain is valid, but root is nottrusted. [`errSSLXCertChainInvalid`](/documentation/Security/errSSLXCertChainInvalid) Invalid certificate chain. [`errSSLPeerUnknownCA`](/documentation/Security/errSSLPeerUnknownCA) An unknown certificate authority was encountered. ### Connection status result codes [`errSSLClientHelloReceived`](/documentation/Security/errSSLClientHelloReceived) A non-fatal result for providing a server name indication. [`errSSLClosedAbort`](/documentation/Security/errSSLClosedAbort) The connection closed due to an error. [`errSSLClosedGraceful`](/documentation/Security/errSSLClosedGraceful) The connection closed gracefully. [`errSSLClosedNoNotify`](/documentation/Security/errSSLClosedNoNotify) The server closed the session with no notification. [`errSSLConnectionRefused`](/documentation/Security/errSSLConnectionRefused) The peer dropped the connection before responding. [`errSSLPeerAuthCompleted`](/documentation/Security/errSSLPeerAuthCompleted) A non-fatal result indicating the peer certificate is valid, or was ignored if verification is disabled. [`errSSLWouldBlock`](/documentation/Security/errSSLWouldBlock) Function is blocked; waiting for I/O. This is not fatal. ### Cryptography result codes [`errSSLCrypto`](/documentation/Security/errSSLCrypto) An underlying cryptographic error was encountered. [`errSSLDecryptionFail`](/documentation/Security/errSSLDecryptionFail) Decryption failed. [`errSSLPeerDecryptError`](/documentation/Security/errSSLPeerDecryptError) A decryption error occurred. [`errSSLPeerDecryptionFail`](/documentation/Security/errSSLPeerDecryptionFail) Decryption failed. [`errSSLWeakPeerEphemeralDHKey`](/documentation/Security/errSSLWeakPeerEphemeralDHKey) Indicates a weak ephemeral dh key. ### Other result codes [`errSSLBadCipherSuite`](/documentation/Security/errSSLBadCipherSuite) A bad SSL cipher suite was encountered. [`errSSLBadConfiguration`](/documentation/Security/errSSLBadConfiguration) A configuration error occurred. [`errSSLBadRecordMac`](/documentation/Security/errSSLBadRecordMac) A record with a bad message authentication code (MAC) was encountered. [`errSSLBufferOverflow`](/documentation/Security/errSSLBufferOverflow) An insufficient buffer was provided. [`errSSLConfigurationFailed`](/documentation/Security/errSSLConfigurationFailed) TLS configuration failed. [`errSSLDecodeError`](/documentation/Security/errSSLDecodeError) Decode failed. [`errSSLDecompressFail`](/documentation/Security/errSSLDecompressFail) Decompression failed. [`errSSLFatalAlert`](/documentation/Security/errSSLFatalAlert) A fatal alert was encountered. [`errSSLHandshakeFail`](/documentation/Security/errSSLHandshakeFail) Handshake failed. [`errSSLIllegalParam`](/documentation/Security/errSSLIllegalParam) An illegal parameter was encountered. [`errSSLInappropriateFallback`](/documentation/Security/errSSLInappropriateFallback) Inappropriate fallback. [`errSSLInternal`](/documentation/Security/errSSLInternal) Internal error. [`errSSLMissingExtension`](/documentation/Security/errSSLMissingExtension) Missing extension. [`errSSLModuleAttach`](/documentation/Security/errSSLModuleAttach) Module attach failure. [`errSSLNegotiation`](/documentation/Security/errSSLNegotiation) The cipher suite negotiation failed. [`errSSLNetworkTimeout`](/documentation/Security/errSSLNetworkTimeout) Network timeout triggered. [`errSSLPeerAccessDenied`](/documentation/Security/errSSLPeerAccessDenied) Access was denied. [`errSSLPeerBadRecordMac`](/documentation/Security/errSSLPeerBadRecordMac) A record with a bad message authentication code (MAC) was encountered. [`errSSLPeerDecodeError`](/documentation/Security/errSSLPeerDecodeError) A decoding error occurred. [`errSSLPeerDecompressFail`](/documentation/Security/errSSLPeerDecompressFail) Decompression failed. [`errSSLPeerExportRestriction`](/documentation/Security/errSSLPeerExportRestriction) An export restriction occurred. [`errSSLPeerHandshakeFail`](/documentation/Security/errSSLPeerHandshakeFail) The handshake failed. [`errSSLPeerInsufficientSecurity`](/documentation/Security/errSSLPeerInsufficientSecurity) There is insufficient security for this operation. [`errSSLPeerInternalError`](/documentation/Security/errSSLPeerInternalError) An internal error occurred. [`errSSLPeerNoRenegotiation`](/documentation/Security/errSSLPeerNoRenegotiation) No renegotiation is allowed. [`errSSLPeerProtocolVersion`](/documentation/Security/errSSLPeerProtocolVersion) A bad protocol version was encountered. [`errSSLPeerRecordOverflow`](/documentation/Security/errSSLPeerRecordOverflow) A record overflow occurred. [`errSSLPeerUnexpectedMsg`](/documentation/Security/errSSLPeerUnexpectedMsg) An unexpected message was received. [`errSSLPeerUserCancelled`](/documentation/Security/errSSLPeerUserCancelled) The user canceled the operation. [`errSSLProtocol`](/documentation/Security/errSSLProtocol) SSL protocol error. [`errSSLRecordOverflow`](/documentation/Security/errSSLRecordOverflow) A record overflow occurred. [`errSSLSessionNotFound`](/documentation/Security/errSSLSessionNotFound) An attempt to restore an unknown session failed. [`errSSLTransportReset`](/documentation/Security/errSSLTransportReset) Transport (socket) shutdown, for example, TCP RST or FIN. [`errSSLUnexpectedMessage`](/documentation/Security/errSSLUnexpectedMessage) Peer rejected unexpected message. [`errSSLUnexpectedRecord`](/documentation/Security/errSSLUnexpectedRecord) [`errSSLUnknownPSKIdentity`](/documentation/Security/errSSLUnknownPSKIdentity) Unknown PSK identity. [`errSSLUnrecognizedName`](/documentation/Security/errSSLUnrecognizedName) Unknown or unrecognized name. [`errSSLUnsupportedExtension`](/documentation/Security/errSSLUnsupportedExtension) Unsupported TLS extension. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)