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CefErrorCode Enumeration
Version 51.0.0
Lists some of the error codes that can be reported by CEF. For a complete up-to-date list, see the CEF source code (cef_errorcode_t in include/internal/cef_types.h) and the Chromium source code (net/base/net_error_list.h).

Namespace: CefSharp
Assembly: CefSharp (in CefSharp.dll) Version: (
public enum CefErrorCode
  Member nameValueDescription
None0 No error occurred.
IoPending-1 An asynchronous IO operation is not yet complete. This usually does not indicate a fatal error. Typically this error will be generated as a notification to wait for some external notification that the IO operation finally completed.
Failed-2 A generic failure occurred.
Aborted-3 A request was aborted, possibly by the user.
InvalidArgument-4 An argument to the function is incorrect.
InvalidHandle-5 The handle or file descriptor is invalid.
FileNotFound-6 The file or directory cannot be found.
TimedOut-7 An operation timed out.
FileTooBig-8 The file is too large.
Unexpected-9 An unexpected error. This may be caused by a programming mistake or an invalid assumption
AccessDenied-10 Permission to access a resource, other than the network, was denied.
NotImplemented-11 The operation failed because of unimplemented functionality.
InsufficientResources-12 There were not enough resources to complete the operation.
OutOfMemory-13 Memory allocation failed.
UploadFileChanged-14 The file upload failed because the file's modification time was different from the expectation.
SocketNotConnected-15 The socket is not connected.
FileExists-16 The file already exists.
FilePathTooLong-17 The path or file name is too long.
FileNoSpace-18 Not enough room left on the disk.
FileVirusInfected-19 The file has a virus.
BlockedByClient-20 The client chose to block the request.
NetworkChanged-21 The network changed.
BlockedByAdministrator-22 The request was blocked by the URL blacklist configured by the domain administrator.
SocketIsConnected-23 The socket is already connected.
BlockedEnrollmentCheckPending-24 The request was blocked because the forced reenrollment check is still pending. This error can only occur on ChromeOS. The error can be emitted by code in chrome/browser/policy/
ConnectionClosed-100 A connection was closed (corresponding to a TCP FIN).
ConnectionReset-101 A connection was reset (corresponding to a TCP RST).
ConnectionRefused-102 A connection attempt was refused.
ConnectionAborted-103 A connection timed out as a result of not receiving an ACK for data sent. This can include a FIN packet that did not get ACK'd.
ConnectionFailed-104 A connection attempt failed.
NameNotResolved-105 The host name could not be resolved.
InternetDisconnected-106 The Internet connection has been lost.
SslProtocolError-107 An SSL protocol error occurred.
AddressInvalid-108 The IP address or port number is invalid (e.g., cannot connect to the IP address 0 or the port 0).
AddressUnreachable-109 The IP address is unreachable. This usually means that there is no route to the specified host or network.
SslClientAuthCertNeeded-110 The server requested a client certificate for SSL client authentication.
TunnelConnectionFailed-111 A tunnel connection through the proxy could not be established.
NoSslVersionsEnabled-112 No SSL protocol versions are enabled.
SslVersionOrCipherMismatch-113 The client and server don't support a common SSL protocol version or cipher suite.
SslRenegotiationRequested-114 The server requested a renegotiation (rehandshake).
ProxyAuthUnsupported-115 The proxy requested authentication (for tunnel establishment) with an unsupported method.
CertErrorInSslRenegotiation-116 During SSL renegotiation (rehandshake), the server sent a certificate with an error. Note: this error is not in the -2xx range so that it won't be handled as a certificate error.
BadSslClientAuthCert-117 The SSL handshake failed because of a bad or missing client certificate.
ConnectionTimedOut-118 A connection attempt timed out.
HostResolverQueueTooLarge-119 There are too many pending DNS resolves, so a request in the queue was aborted.
SocksConnectionFailed-120 Failed establishing a connection to the SOCKS proxy server for a target host.
SocksConnectionHostUnreachable-121 The SOCKS proxy server failed establishing connection to the target host because that host is unreachable.
NpnNegotiationFailed-122 The request to negotiate an alternate protocol failed.
SslNoRenegotiation-123 The peer sent an SSL no_renegotiation alert message.
WinsockUnexpectedWrittenBytes-124 Winsock sometimes reports more data written than passed. This is probably due to a broken LSP.
SslDecompressionFailureAlert-125 An SSL peer sent us a fatal decompression_failure alert. This typically occurs when a peer selects DEFLATE compression in the mistaken belief that it supports it.
SslBadRecordMacAlert-126 An SSL peer sent us a fatal bad_record_mac alert. This has been observed from servers with buggy DEFLATE support.
ProxyAuthRequested-127 The proxy requested authentication (for tunnel establishment).
SslUnsafeNegotiation-128 A known TLS strict server didn't offer the renegotiation extension.
SslWeakServerEphemeralDhKey-129 The SSL server attempted to use a weak ephemeral Diffie-Hellman key.
ProxyConnectionFailed-130 Could not create a connection to the proxy server. An error occurred either in resolving its name, or in connecting a socket to it. Note that this does NOT include failures during the actual "CONNECT" method of an HTTP proxy.
MandatoryProxyConfigurationFailed-131 A mandatory proxy configuration could not be used. Currently this means that a mandatory PAC script could not be fetched, parsed or executed.
PreconnectMaxSocketLimit-133 We've hit the max socket limit for the socket pool while preconnecting. We don't bother trying to preconnect more sockets.
SslClientAuthPrivateKeyAccessDenied-134 The permission to use the SSL client certificate's private key was denied.
SslClientAuthCertNoPrivateKey-135 The SSL client certificate has no private key.
ProxyCertificateInvalid-136 The certificate presented by the HTTPS Proxy was invalid.
NameResolutionFailed-137 An error occurred when trying to do a name resolution (DNS).
NetworkAccessDenied-138 Permission to access the network was denied. This is used to distinguish errors that were most likely caused by a firewall from other access denied errors. See also ERR_ACCESS_DENIED.
TemporarilyThrottled-139 The request throttler module cancelled this request to avoid DDOS.
HttpsProxyTunnelResponse-140 A request to create an SSL tunnel connection through the HTTPS proxy received a non-200 (OK) and non-407 (Proxy Auth) response. The response body might include a description of why the request failed.
SslClientAuthSignatureFailed-141 We were unable to sign the CertificateVerify data of an SSL client auth handshake with the client certificate's private key. Possible causes for this include the user implicitly or explicitly denying access to the private key, the private key may not be valid for signing, the key may be relying on a cached handle which is no longer valid, or the CSP won't allow arbitrary data to be signed.
MsgTooBig-142 The message was too large for the transport. (for example a UDP message which exceeds size threshold).
SpdySessionAlreadyExists-143 A SPDY session already exists, and should be used instead of this connection.
WsProtocolError-145 Websocket protocol error. Indicates that we are terminating the connection due to a malformed frame or other protocol violation.
ProtocolSwitched-146 Connection was aborted for switching to another ptotocol. WebSocket abort SocketStream connection when alternate protocol is found.
AddressInUse-147 Returned when attempting to bind an address that is already in use.
SslHandshakeNotCompleted-148 An operation failed because the SSL handshake has not completed.
SslBadPeerPublicKey-149 SSL peer's public key is invalid.
SslPinnedKeyNotInCertChain-150 The certificate didn't match the built-in public key pins for the host name. The pins are set in net/http/ and require that one of a set of public keys exist on the path from the leaf to the root.
ClientAuthCertTypeUnsupported-151 Server request for client certificate did not contain any types we support.
OriginBoundCertGenerationTypeMismatch-152 Server requested one type of cert, then requested a different type while the first was still being generated.
SslDecryptErrorAlert-153 An SSL peer sent us a fatal decrypt_error alert. This typically occurs when a peer could not correctly verify a signature (in CertificateVerify or ServerKeyExchange) or validate a Finished message.
WsThrottleQueueTooLarge-154 There are too many pending WebSocketJob instances, so the new job was not pushed to the queue.
TooManySocketStreams-155 There are too many active SocketStream instances, so the new connect request was rejected.
SslServerCertChanged-156 The SSL server certificate changed in a renegotiation.
SslInappropriateFallback-157 The SSL server indicated that an unnecessary TLS version fallback was performed.
CtNoSctsVerifiedOk-158 Certificate Transparency: All Signed Certificate Timestamps failed to verify.
SslUnrecognizedNameAlert-159 The SSL server sent us a fatal unrecognized_name alert.
SocketSetReceiveBufferSizeError-160 Failed to set the socket's receive buffer size as requested.
SocketSetSendBufferSizeError-161 Failed to set the socket's send buffer size as requested.
SocketReceiveBufferSizeUnchangeable-162 Failed to set the socket's receive buffer size as requested, despite success return code from setsockopt.
SocketSendBufferSizeUnchangeable-163 Failed to set the socket's send buffer size as requested, despite success return code from setsockopt.
SslClientAuthCertBadFormat-164 Failed to import a client certificate from the platform store into the SSL library.
CertCommonNameInvalid-200 The server responded with a certificate whose common name did not match the host name. This could mean: 1. An attacker has redirected our traffic to his server and is presenting a certificate for which he knows the private key. 2. The server is misconfigured and responding with the wrong cert. 3. The user is on a wireless network and is being redirected to the network's login page. 4. The OS has used a DNS search suffix and the server doesn't have a certificate for the abbreviated name in the address bar.
CertDateInvalid-201 The server responded with a certificate that, by our clock, appears to either not yet be valid or to have expired. This could mean: 1. An attacker is presenting an old certificate for which he has managed to obtain the private key 2. The server is misconfigured and is not presenting a valid cert. 3. Our clock is wrong.
CertAuthorityInvalid-202 The server responded with a certificate that is signed by an authority we don't trust. The could mean: 1. An attacker has substituted the real certificate for a cert that contains his public key and is signed by his cousin. 2. The server operator has a legitimate certificate from a CA we don't know about, but should trust. 3. The server is presenting a self-signed certificate, providing no defense against active attackers (but foiling passive attackers).
CertContainsErrors-203 The server responded with a certificate that contains errors. This error is not recoverable. MSDN describes this error as follows: "The SSL certificate contains errors." NOTE: It's unclear how this differs from ERR_CERT_INVALID. For consistency, use that code instead of this one from now on.
CertNoRevocationMechanism-204 The certificate has no mechanism for determining if it is revoked. In effect, this certificate cannot be revoked.
CertUnableToCheckRevocation-205 Revocation information for the security certificate for this site is not available. This could mean: 1. An attacker has compromised the private key in the certificate and is blocking our attempt to find out that the cert was revoked. 2. The certificate is unrevoked, but the revocation server is busy or unavailable.
CertRevoked-206 The server responded with a certificate has been revoked. We have the capability to ignore this error, but it is probably not the thing to do.
CertInvalid-207 The server responded with a certificate that is invalid. This error is not recoverable.
CertWeakSignatureAlgorithm-208 The server responded with a certificate that is signed using a weak signature algorithm.
CertNonUniqueName-210 The host name specified in the certificate is not unique.
CertWeakKey-211 The server responded with a certificate that contains a weak key (e.g. a too-small RSA key).
CertNameConstraintViolation-212 The certificate claimed DNS names that are in violation of name constraints.
CertEnd-213 Add new certificate error codes here. Update the value of CERT_END whenever you add a new certificate error code. The value immediately past the last certificate error code.
InvalidUrl-300 The URL is invalid.
DisallowedUrlScheme-301 The scheme of the URL is disallowed.
UnknownUrlScheme-302 The scheme of the URL is unknown.
TooManyRedirects-310 Attempting to load an URL resulted in too many redirects.
UnsafeRedirect-311 Attempting to load an URL resulted in an unsafe redirect (e.g., a redirect to file:// is considered unsafe).
UnsafePort-312 Attempting to load an URL with an unsafe port number. These are port numbers that correspond to services, which are not robust to spurious input that may be constructed as a result of an allowed web construct (e.g., HTTP looks a lot like SMTP, so form submission to port 25 is denied).
InvalidResponse-320 The server's response was invalid.
InvalidChunkedEncoding-321 Error in chunked transfer encoding.
MethodNotSupported-322 The server did not support the request method.
UnexpectedProxyAuth-323 The response was 407 (Proxy Authentication Required), yet we did not send the request to a proxy.
EmptyResponse-324 The server closed the connection without sending any data.
ResponseHeadersTooBig-325 The headers section of the response is too large.
PacStatusNotOk-326 The PAC requested by HTTP did not have a valid status code (non-200).
PacScriptFailed-327 The evaluation of the PAC script failed.
RequestRangeNotSatisfiable-328 The response was 416 (Requested range not satisfiable) and the server cannot satisfy the range requested.
MalformedIdentity-329 The identity used for authentication is invalid.
ContentDecodingFailed-330 Content decoding of the response body failed.
NetworkIoSuspended-331 An operation could not be completed because all network IO is suspended.
SynReplyNotReceived-332 FLIP data received without receiving a SYN_REPLY on the stream.
EncodingConversionFailed-333 Converting the response to target encoding failed.
UnrecognizedFtpDirectoryListingFormat-334 The server sent an FTP directory listing in a format we do not understand.
InvalidSpdyStream-335 Attempted use of an unknown SPDY stream id.
NoSupportedProxies-336 There are no supported proxies in the provided list.
SpdyProtocolError-337 There is a SPDY protocol error.
InvalidAuthCredentials-338 Credentials could not be established during HTTP Authentication.
UnsupportedAuthScheme-339 An HTTP Authentication scheme was tried which is not supported on this machine.
EncodingDetectionFailed-340 Detecting the encoding of the response failed.
MissingAuthCredentials-341 (GSSAPI) No Kerberos credentials were available during HTTP Authentication.
UnexpectedSecurityLibraryStatus-342 An unexpected, but documented, SSPI or GSSAPI status code was returned.
MisconfiguredAuthEnvironment-343 The environment was not set up correctly for authentication (for example, no KDC could be found or the principal is unknown.
UndocumentedSecurityLibraryStatus-344 An undocumented SSPI or GSSAPI status code was returned.
ResponseBodyTooBigToDrain-345 The HTTP response was too big to drain.
ResponseHeadersMultipleContentLength-346 The HTTP response contained multiple distinct Content-Length headers.
IncompleteSpdyHeaders-347 SPDY Headers have been received, but not all of them - status or version headers are missing, so we're expecting additional frames to complete them.
PacNotInDhcp-348 No PAC URL configuration could be retrieved from DHCP. This can indicate either a failure to retrieve the DHCP configuration, or that there was no PAC URL configured in DHCP.
ResponseHeadersMultipleContentDisposition-349 The HTTP response contained multiple Content-Disposition headers.
ResponseHeadersMultipleLocation-350 The HTTP response contained multiple Location headers.
SpdyServerRefusedStream-351 SPDY server refused the stream. Client should retry. This should never be a user-visible error.
SpdyPingFailed-352 SPDY server didn't respond to the PING message.
ContentLengthMismatch-354 The HTTP response body transferred fewer bytes than were advertised by the Content-Length header when the connection is closed.
IncompleteChunkedEncoding-355 The HTTP response body is transferred with Chunked-Encoding, but the terminating zero-length chunk was never sent when the connection is closed.
QuicProtocolError-356 There is a QUIC protocol error.
ResponseHeadersTruncated-357 The HTTP headers were truncated by an EOF.
QuicHandshakeFailed-358 The QUIC crytpo handshake failed. This means that the server was unable to read any requests sent, so they may be resent.
RequestForSecureResourceOverInsecureQuic-359 An https resource was requested over an insecure QUIC connection.
SpdyInadequateTransportSecurity-360 Transport security is inadequate for the SPDY version.
SpdyFlowControlError-361 The peer violated SPDY flow control.
SpdyFrameSizeError-362 The peer sent an improperly sized SPDY frame.
SpdyCompressionError-363 Decoding or encoding of compressed SPDY headers failed.
ProxyAuthRequestedWithNoConnection-364 Proxy Auth Requested without a valid Client Socket Handle.
CacheMiss-400 The cache does not have the requested entry.
CacheReadFailure-401 Unable to read from the disk cache.
CacheWriteFailure-402 Unable to write to the disk cache.
CacheOperationNotSupported-403 The operation is not supported for this entry.
CacheOpenFailure-404 The disk cache is unable to open this entry.
CacheCreateFailure-405 The disk cache is unable to create this entry.
CacheRace-406 Multiple transactions are racing to create disk cache entries. This is an internal error returned from the HttpCache to the HttpCacheTransaction that tells the transaction to restart the entry-creation logic because the state of the cache has changed.
CacheChecksumReadFailure-407 The cache was unable to read a checksum record on an entry. This can be returned from attempts to read from the cache. It is an internal error, returned by the SimpleCache backend, but not by any URLRequest methods or members.
CacheChecksumMismatch-408 The cache found an entry with an invalid checksum. This can be returned from attempts to read from the cache. It is an internal error, returned by the SimpleCache backend, but not by any URLRequest methods or members.
CacheLockTimeout-409 Internal error code for the HTTP cache. The cache lock timeout has fired.
InsecureResponse-501 The server's response was insecure (e.g. there was a cert error).
NoPrivateKeyForCert-502 The server responded to a <keygen> with a generated client cert that we don't have the matching private key for.
AddUserCertFailed-503 An error adding to the OS certificate database (e.g. OS X Keychain).
FtpFailed-601 A generic error for failed FTP control connection command. If possible, please use or add a more specific error code.
FtpServiceUnavailable-602 The server cannot fulfill the request at this point. This is a temporary error. FTP response code 421.
FtpTransferAborted-603 The server has aborted the transfer. FTP response code 426.
FtpFileBusy-604 The file is busy, or some other temporary error condition on opening the file. FTP response code 450.
FtpSyntaxError-605 Server rejected our command because of syntax errors. FTP response codes 500, 501.
FtpCommandNotSupported-606 Server does not support the command we issued. FTP response codes 502, 504.
FtpBadCommandSequence-607 Server rejected our command because we didn't issue the commands in right order. FTP response code 503.
Pkcs12ImportBadPassword-701 PKCS #12 import failed due to incorrect password.
Pkcs12ImportFailed-702 PKCS #12 import failed due to other error.
ImportCaCertNotCa-703 CA import failed - not a CA cert.
ImportCertAlreadyExists-704 Import failed - certificate already exists in database. Note it's a little weird this is an error but reimporting a PKCS12 is ok (no-op). That's how Mozilla does it, though.
ImportCaCertFailed-705 CA import failed due to some other error.
ImportServerCertFailed-706 Server certificate import failed due to some internal error.
Pkcs12ImportInvalidMac-707 PKCS #12 import failed due to invalid MAC.
Pkcs12ImportInvalidFile-708 PKCS #12 import failed due to invalid/corrupt file.
Pkcs12ImportUnsupported-709 PKCS #12 import failed due to unsupported features.
KeyGenerationFailed-710 Key generation failed.
OriginBoundCertGenerationFailed-711 Server-bound certificate generation failed.
PrivateKeyExportFailed-712 Failure to export private key.
SelfSignedCertGenerationFailed-713 Self-signed certificate generation failed.
CertDatabaseChanged-714 The certificate database changed in some way.
ChannelIdImportFailed-715 Failure to import Channel ID.
DnsMalformedResponse-800 DNS resolver received a malformed response.
DnsServerRequiresTcp-801 DNS server requires TCP
DnsServerFailed-802 DNS server failed. This error is returned for all of the following error conditions: 1 - Format error - The name server was unable to interpret the query. 2 - Server failure - The name server was unable to process this query due to a problem with the name server. 4 - Not Implemented - The name server does not support the requested kind of query. 5 - Refused - The name server refuses to perform the specified operation for policy reasons.
DnsTimedOut-803 DNS transaction timed out.
DnsCacheMiss-804 The entry was not found in cache, for cache-only lookups.
DnsSearchEmpty-805 Suffix search list rules prevent resolution of the given host name.
DnsSortError-806 Failed to sort addresses according to RFC3484.
See Also