libcurl-errors - error codes in libcurl
This man page includes most, if not all, available error codes in libcurl. Why
they occur and possibly what you can do to fix the problem are also included.
Almost all "easy" interface functions return a CURLcode error code. No
matter what, using the
curl_easy_setopt(3) option
CURLOPT_ERRORBUFFER(3) is a good idea as it will give you a human
readable error string that may offer more details about the cause of the error
than just the error code.
curl_easy_strerror(3) can be called to get an
error string from a given CURLcode number.
CURLcode is one of the following:
- CURLE_OK (0)
- All fine. Proceed as usual.
- CURLE_UNSUPPORTED_PROTOCOL (1)
- The URL you passed to libcurl used a protocol that this
libcurl does not support. The support might be a compile-time option that
you did not use, it can be a misspelled protocol string or just a protocol
libcurl has no code for.
- CURLE_FAILED_INIT (2)
- Early initialization code failed. This is likely to be an
internal error or problem, or a resource problem where something
fundamental could not get done at init time.
- CURLE_URL_MALFORMAT (3)
- The URL was not properly formatted.
- CURLE_NOT_BUILT_IN (4)
- A requested feature, protocol or option was not found
built-in in this libcurl due to a build-time decision. This means that a
feature or option was not enabled or explicitly disabled when libcurl was
built and in order to get it to function you have to get a rebuilt
libcurl.
- CURLE_COULDNT_RESOLVE_PROXY (5)
- Could not resolve proxy. The given proxy host could not be
resolved.
- CURLE_COULDNT_RESOLVE_HOST (6)
- Could not resolve host. The given remote host was not
resolved.
- CURLE_COULDNT_CONNECT (7)
- Failed to connect() to host or proxy.
- CURLE_WEIRD_SERVER_REPLY (8)
- The server sent data libcurl could not parse. This error
code was known as CURLE_FTP_WEIRD_SERVER_REPLY before 7.51.0.
- CURLE_REMOTE_ACCESS_DENIED (9)
- We were denied access to the resource given in the URL. For
FTP, this occurs while trying to change to the remote directory.
- CURLE_FTP_ACCEPT_FAILED (10)
- While waiting for the server to connect back when an active
FTP session is used, an error code was sent over the control connection or
similar.
- CURLE_FTP_WEIRD_PASS_REPLY (11)
- After having sent the FTP password to the server, libcurl
expects a proper reply. This error code indicates that an unexpected code
was returned.
- CURLE_FTP_ACCEPT_TIMEOUT (12)
- During an active FTP session while waiting for the server
to connect, the CURLOPT_ACCEPTTIMEOUT_MS(3) (or the internal
default) timeout expired.
- CURLE_FTP_WEIRD_PASV_REPLY (13)
- libcurl failed to get a sensible result back from the
server as a response to either a PASV or a EPSV command. The server is
flawed.
- CURLE_FTP_WEIRD_227_FORMAT (14)
- FTP servers return a 227-line as a response to a PASV
command. If libcurl fails to parse that line, this return code is passed
back.
- CURLE_FTP_CANT_GET_HOST (15)
- An internal failure to lookup the host used for the new
connection.
- CURLE_HTTP2 (16)
- A problem was detected in the HTTP2 framing layer. This is
somewhat generic and can be one out of several problems, see the error
buffer for details.
- CURLE_FTP_COULDNT_SET_TYPE (17)
- Received an error when trying to set the transfer mode to
binary or ASCII.
- CURLE_PARTIAL_FILE (18)
- A file transfer was shorter or larger than expected. This
happens when the server first reports an expected transfer size, and then
delivers data that does not match the previously given size.
- CURLE_FTP_COULDNT_RETR_FILE (19)
- This was either a weird reply to a 'RETR' command or a zero
byte transfer complete.
- Obsolete error (20)
- Not used in modern versions.
- CURLE_QUOTE_ERROR (21)
- When sending custom "QUOTE" commands to the
remote server, one of the commands returned an error code that was 400 or
higher (for FTP) or otherwise indicated unsuccessful completion of the
command.
- CURLE_HTTP_RETURNED_ERROR (22)
- This is returned if CURLOPT_FAILONERROR(3) is set
TRUE and the HTTP server returns an error code that is >= 400.
- CURLE_WRITE_ERROR (23)
- An error occurred when writing received data to a local
file, or an error was returned to libcurl from a write callback.
- Obsolete error (24)
- Not used in modern versions.
- CURLE_UPLOAD_FAILED (25)
- Failed starting the upload. For FTP, the server typically
denied the STOR command. The error buffer usually contains the server's
explanation for this.
- CURLE_READ_ERROR (26)
- There was a problem reading a local file or an error
returned by the read callback.
- CURLE_OUT_OF_MEMORY (27)
- A memory allocation request failed. This is serious badness
and things are severely screwed up if this ever occurs.
- CURLE_OPERATION_TIMEDOUT (28)
- Operation timeout. The specified time-out period was
reached according to the conditions.
- Obsolete error (29)
- Not used in modern versions.
- CURLE_FTP_PORT_FAILED (30)
- The FTP PORT command returned error. This mostly happens
when you have not specified a good enough address for libcurl to use. See
CURLOPT_FTPPORT(3).
- CURLE_FTP_COULDNT_USE_REST (31)
- The FTP REST command returned error. This should never
happen if the server is sane.
- Obsolete error (32)
- Not used in modern versions.
- CURLE_RANGE_ERROR (33)
- The server does not support or accept range requests.
- CURLE_HTTP_POST_ERROR (34)
- This is an odd error that mainly occurs due to internal
confusion.
- CURLE_SSL_CONNECT_ERROR (35)
- A problem occurred somewhere in the SSL/TLS handshake. You
really want the error buffer and read the message there as it pinpoints
the problem slightly more. Could be certificates (file formats, paths,
permissions), passwords, and others.
- CURLE_BAD_DOWNLOAD_RESUME (36)
- The download could not be resumed because the specified
offset was out of the file boundary.
- CURLE_FILE_COULDNT_READ_FILE (37)
- A file given with FILE:// could not be opened. Most likely
because the file path does not identify an existing file. Did you check
file permissions?
- CURLE_LDAP_CANNOT_BIND (38)
- LDAP cannot bind. LDAP bind operation failed.
- CURLE_LDAP_SEARCH_FAILED (39)
- LDAP search failed.
- Obsolete error (40)
- Not used in modern versions.
- CURLE_FUNCTION_NOT_FOUND (41)
- Function not found. A required zlib function was not
found.
- CURLE_ABORTED_BY_CALLBACK (42)
- Aborted by callback. A callback returned "abort"
to libcurl.
- CURLE_BAD_FUNCTION_ARGUMENT (43)
- A function was called with a bad parameter.
- Obsolete error (44)
- Not used in modern versions.
- CURLE_INTERFACE_FAILED (45)
- Interface error. A specified outgoing interface could not
be used. Set which interface to use for outgoing connections' source IP
address with CURLOPT_INTERFACE(3).
- Obsolete error (46)
- Not used in modern versions.
- CURLE_TOO_MANY_REDIRECTS (47)
- Too many redirects. When following redirects, libcurl hit
the maximum amount. Set your limit with CURLOPT_MAXREDIRS(3).
- CURLE_UNKNOWN_OPTION (48)
- An option passed to libcurl is not recognized/known. Refer
to the appropriate documentation. This is most likely a problem in the
program that uses libcurl. The error buffer might contain more specific
information about which exact option it concerns.
- CURLE_SETOPT_OPTION_SYNTAX (49)
- An option passed in to a setopt was wrongly formatted. See
error message for details about what option.
- Obsolete errors (50-51)
- Not used in modern versions.
- CURLE_GOT_NOTHING (52)
- Nothing was returned from the server, and under the
circumstances, getting nothing is considered an error.
- CURLE_SSL_ENGINE_NOTFOUND (53)
- The specified crypto engine was not found.
- CURLE_SSL_ENGINE_SETFAILED (54)
- Failed setting the selected SSL crypto engine as
default.
- CURLE_SEND_ERROR (55)
- Failed sending network data.
- CURLE_RECV_ERROR (56)
- Failure with receiving network data.
- Obsolete error (57)
- Not used in modern versions.
- CURLE_SSL_CERTPROBLEM (58)
- problem with the local client certificate.
- CURLE_SSL_CIPHER (59)
- Could not use specified cipher.
- CURLE_PEER_FAILED_VERIFICATION (60)
- The remote server's SSL certificate or SSH fingerprint was
deemed not OK. This error code has been unified with CURLE_SSL_CACERT
since 7.62.0. Its previous value was 51.
- CURLE_BAD_CONTENT_ENCODING (61)
- Unrecognized transfer encoding.
- Obsolete error (62)
- Not used in modern versions.
- CURLE_FILESIZE_EXCEEDED (63)
- Maximum file size exceeded.
- CURLE_USE_SSL_FAILED (64)
- Requested FTP SSL level failed.
- CURLE_SEND_FAIL_REWIND (65)
- When doing a send operation curl had to rewind the data to
retransmit, but the rewinding operation failed.
- CURLE_SSL_ENGINE_INITFAILED (66)
- Initiating the SSL Engine failed.
- CURLE_LOGIN_DENIED (67)
- The remote server denied curl to login (Added in
7.13.1)
- CURLE_TFTP_NOTFOUND (68)
- File not found on TFTP server.
- CURLE_TFTP_PERM (69)
- Permission problem on TFTP server.
- CURLE_REMOTE_DISK_FULL (70)
- Out of disk space on the server.
- CURLE_TFTP_ILLEGAL (71)
- Illegal TFTP operation.
- CURLE_TFTP_UNKNOWNID (72)
- Unknown TFTP transfer ID.
- CURLE_REMOTE_FILE_EXISTS (73)
- File already exists and will not be overwritten.
- CURLE_TFTP_NOSUCHUSER (74)
- This error should never be returned by a properly
functioning TFTP server.
- Obsolete error (75-76)
- Not used in modern versions.
- CURLE_SSL_CACERT_BADFILE (77)
- Problem with reading the SSL CA cert (path? access
rights?)
- CURLE_REMOTE_FILE_NOT_FOUND (78)
- The resource referenced in the URL does not exist.
- CURLE_SSH (79)
- An unspecified error occurred during the SSH session.
- CURLE_SSL_SHUTDOWN_FAILED (80)
- Failed to shut down the SSL connection.
- CURLE_AGAIN (81)
- Socket is not ready for send/recv wait till it's ready and
try again. This return code is only returned from curl_easy_recv(3)
and curl_easy_send(3) (Added in 7.18.2)
- CURLE_SSL_CRL_BADFILE (82)
- Failed to load CRL file (Added in 7.19.0)
- CURLE_SSL_ISSUER_ERROR (83)
- Issuer check failed (Added in 7.19.0)
- CURLE_FTP_PRET_FAILED (84)
- The FTP server does not understand the PRET command at all
or does not support the given argument. Be careful when using
CURLOPT_CUSTOMREQUEST(3), a custom LIST command will be sent with
the PRET command before PASV as well. (Added in 7.20.0)
- CURLE_RTSP_CSEQ_ERROR (85)
- Mismatch of RTSP CSeq numbers.
- CURLE_RTSP_SESSION_ERROR (86)
- Mismatch of RTSP Session Identifiers.
- CURLE_FTP_BAD_FILE_LIST (87)
- Unable to parse FTP file list (during FTP wildcard
downloading).
- CURLE_CHUNK_FAILED (88)
- Chunk callback reported error.
- CURLE_NO_CONNECTION_AVAILABLE (89)
- (For internal use only, will never be returned by libcurl)
No connection available, the session will be queued. (added in
7.30.0)
- CURLE_SSL_PINNEDPUBKEYNOTMATCH (90)
- Failed to match the pinned key specified with
CURLOPT_PINNEDPUBLICKEY(3).
- CURLE_SSL_INVALIDCERTSTATUS (91)
- Status returned failure when asked with
CURLOPT_SSL_VERIFYSTATUS(3).
- CURLE_HTTP2_STREAM (92)
- Stream error in the HTTP/2 framing layer.
- CURLE_RECURSIVE_API_CALL (93)
- An API function was called from inside a callback.
- CURLE_AUTH_ERROR (94)
- An authentication function returned an error.
- CURLE_HTTP3 (95)
- A problem was detected in the HTTP/3 layer. This is
somewhat generic and can be one out of several problems, see the error
buffer for details.
- CURLE_QUIC_CONNECT_ERROR (96)
- QUIC connection error. This error may be caused by an SSL
library error. QUIC is the protocol used for HTTP/3 transfers.
- CURLE_PROXY (97)
- Proxy handshake error. CURLINFO_PROXY_ERROR(3)
provides extra details on the specific problem.
- CURLE_SSL_CLIENTCERT (98)
- SSL Client Certificate required.
- CURLE_UNRECOVERABLE_POLL (99)
- An internal call to poll() or select() returned error that
is not recoverable.
- CURLE_OBSOLETE*
- These error codes will never be returned. They were used in
an old libcurl version and are currently unused.
This is the generic return code used by functions in the libcurl multi
interface. Also consider
curl_multi_strerror(3).
- CURLM_CALL_MULTI_PERFORM (-1)
- This is not really an error. It means you should call
curl_multi_perform(3) again without doing select() or similar in
between. Before version 7.20.0 (released on February 9 2010) this could be
returned by curl_multi_perform(3), but in later versions this
return code is never used.
- CURLM_CALL_MULTI_SOCKET (-1)
- An alias for CURLM_CALL_MULTI_PERFORM. Never
returned by modern libcurl versions.
- CURLM_OK (0)
- Things are fine.
- CURLM_BAD_HANDLE (1)
- The passed-in handle is not a valid CURLM
handle.
- CURLM_BAD_EASY_HANDLE (2)
- An easy handle was not good/valid. It could mean that it is
not an easy handle at all, or possibly that the handle already is in use
by this or another multi handle.
- CURLM_OUT_OF_MEMORY (3)
- You are doomed.
- CURLM_INTERNAL_ERROR (4)
- This can only be returned if libcurl bugs. Please report it
to us!
- CURLM_BAD_SOCKET (5)
- The passed-in socket is not a valid one that libcurl
already knows about. (Added in 7.15.4)
- CURLM_UNKNOWN_OPTION (6)
- curl_multi_setopt() with unsupported option (Added in
7.15.4)
- CURLM_ADDED_ALREADY (7)
- An easy handle already added to a multi handle was
attempted to get added a second time. (Added in 7.32.1)
- CURLM_RECURSIVE_API_CALL (8)
- An API function was called from inside a callback.
- CURLM_WAKEUP_FAILURE (9)
- Wake up is unavailable or failed.
- CURLM_BAD_FUNCTION_ARGUMENT (10)
- A function was called with a bad parameter.
- CURLM_ABORTED_BY_CALLBACK (11)
- A multi handle callback returned error.
- CURLM_UNRECOVERABLE_POLL (12)
- An internal call to poll() or select() returned error that
is not recoverable.
The "share" interface will return a
CURLSHcode to indicate when
an error has occurred. Also consider
curl_share_strerror(3).
- CURLSHE_OK (0)
- All fine. Proceed as usual.
- CURLSHE_BAD_OPTION (1)
- An invalid option was passed to the function.
- CURLSHE_IN_USE (2)
- The share object is currently in use.
- CURLSHE_INVALID (3)
- An invalid share object was passed to the function.
- CURLSHE_NOMEM (4)
- Not enough memory was available. (Added in 7.12.0)
- CURLSHE_NOT_BUILT_IN (5)
- The requested sharing could not be done because the library
you use do not have that particular feature enabled. (Added in
7.23.0)
The URL interface will return a
CURLUcode to indicate when an error has
occurred. Also consider
curl_url_strerror(3).
- CURLUE_BAD_HANDLE (1)
- An invalid URL handle was passed as argument.
- CURLUE_BAD_PARTPOINTER (2)
- An invalid 'part' argument was passed as argument.
- CURLUE_MALFORMED_INPUT (3)
- A malformed input was passed to a URL API function.
- CURLUE_BAD_PORT_NUMBER (4)
- The port number was not a decimal number between 0 and
65535.
- CURLUE_UNSUPPORTED_SCHEME (5)
- This libcurl build does not support the given URL
scheme.
- CURLUE_URLDECODE (6)
- URL decode error, most likely because of rubbish in the
input.
- CURLUE_OUT_OF_MEMORY (7)
- A memory function failed.
- CURLUE_USER_NOT_ALLOWED (8)
- Credentials was passed in the URL when prohibited.
- CURLUE_UNKNOWN_PART (9)
- An unknown part ID was passed to a URL API function.
- CURLUE_NO_SCHEME (10)
- There is no scheme part in the URL.
- CURLUE_NO_USER (11)
- There is no user part in the URL.
- CURLUE_NO_PASSWORD (12)
- There is no password part in the URL.
- CURLUE_NO_OPTIONS (13)
- There is no options part in the URL.
- CURLUE_NO_HOST (14)
- There is no host part in the URL.
- CURLUE_NO_PORT (15)
- There is no port part in the URL.
- CURLUE_NO_QUERY (16)
- There is no query part in the URL.
- CURLUE_NO_FRAGMENT (17)
- There is no fragment part in the URL.
- CURLUE_NO_ZONEID (18)
- There is no zone id set in the URL.
- CURLUE_BAD_FILE_URL (19)
- The file:// URL is invalid.
- CURLUE_BAD_FRAGMENT (20)
- The fragment part of the URL contained bad or invalid
characters.
- CURLUE_BAD_HOSTNAME (21)
- The hostname contained bad or invalid characters.
- CURLUE_BAD_IPV6 (22)
- The IPv6 address hostname contained bad or invalid
characters.
- CURLUE_BAD_LOGIN (23)
- The login part of the URL contained bad or invalid
characters.
- CURLUE_BAD_PASSWORD (24)
- The password part of the URL contained bad or invalid
characters.
- CURLUE_BAD_PATH (25)
- The path part of the URL contained bad or invalid
characters.
- CURLUE_BAD_QUERY (26)
- The query part of the URL contained bad or invalid
characters.
- CURLUE_BAD_SCHEME (27)
- The scheme part of the URL contained bad or invalid
characters.
- CURLUE_BAD_SLASHES (28)
- The URL contained an invalid number of slashes.
- CURLUE_BAD_USER (29)
- The user part of the URL contained bad or invalid
characters.
curl_easy_strerror(3),
curl_multi_strerror(3),
curl_share_strerror(3),
curl_url_strerror(3),
CURLOPT_ERRORBUFFER(3),
CURLOPT_VERBOSE(3),
CURLOPT_DEBUGFUNCTION(3)