Provided by: libmongoc-doc_2.2.0-1_all 
DESCRIPTION
Many C Driver functions report errors by returning false or -1 and filling out a bson_error_t <https://
www.mongoc.org/libbson/current/bson_error_t.html> structure with an error domain, error code, and
message. Use domain to determine which subsystem generated the error, and code for the specific error.
message is a human-readable error description.
See also:
Handling Errors in libbson <https://www.mongodb.com/docs/languages/c/c-driver/current/libbson/tutorials/errors/>.
┌─────────────────────────────────────┬──────────────────────────────────────────────┬───────────────────────────────────────────┐
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_CLIENT │ MONGOC_ERROR_CLIENT_TOO_BIG │ You tried to send a message │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_AUTHENTICATE │ Wrong credentials, or │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_NO_ACCEPTABLE_PEER │ You tried an TLS connection │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_IN_EXHAUST │ You began iterating an │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_SESSION_FAILURE │ Failure related to creating │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_INVALID_ENCRYPTION_ARG │ Failure related to arguments │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_INVALID_ENCRYPTION_STATE │ Failure related to In-Use │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_INVALID_LOAD_BALANCER │ You attempted to connect to │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CLIENT_NOT_READY │ You attempted to create a │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_STREAM │ MONGOC_ERROR_STREAM_NAME_RESOLUTION │ DNS failure. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_STREAM_SOCKET │ Timeout communicating with │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_STREAM_CONNECT │ Failed to connect to server. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_PROTOCOL │ MONGOC_ERROR_PROTOCOL_INVALID_REPLY │ Corrupt response from │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_PROTOCOL_BAD_WIRE_VERSION │ The server version is too │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_CURSOR │ MONGOC_ERROR_CURSOR_INVALID_CURSOR │ You passed bad arguments to │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_CHANGE_STREAM_NO_RESUME_TOKEN │ A resume token was not returned in │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_QUERY │ MONGOC_ERROR_QUERY_FAILURE │ Error API Version 1: Server error │
│ │ │ error message is in message. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SERVER │ MONGOC_ERROR_QUERY_FAILURE │ Error API Version 2: Server error │
│ │ │ error message is in message. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SASL │ A SASL error code. │ man sasl_errors for a list of │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_BSON │ MONGOC_ERROR_BSON_INVALID │ You passed an invalid or oversized │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_NAMESPACE │ MONGOC_ERROR_NAMESPACE_INVALID │ You tried to create a collection │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_COMMAND │ MONGOC_ERROR_COMMAND_INVALID_ARG │ Many functions set this error code │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_PROTOCOL_BAD_WIRE_VERSION │ You tried to use a command option │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_DUPLICATE_KEY │ An insert or update failed because │
│ │ │ because of a duplicate _id or │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_MAX_TIME_MS_EXPIRED │ The operation failed because │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_SERVER_SELECTION_INVALID_ID │ The serverId option for an │
│ │ │ sessionId option). │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_COMMAND │ Error code from server <https://github.com/ │ Error API Version 1: Server error │
│ │ error_codes.yml>. │ message is in message. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SERVER │ Error code from server <https://github.com/ │ Error API Version 2: Server error │
│ │ error_codes.yml>. │ message is in message. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_COLLECTION │ MONGOC_ERROR_COLLECTION_INSERT_FAILED, │ Invalid or empty input to │
│ │ MONGOC_ERROR_COLLECTION_UPDATE_FAILED, │ mongoc_collection_insert_one() <>, │
│ │ MONGOC_ERROR_COLLECTION_DELETE_FAILED. │ mongoc_collection_insert_many() │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_COLLECTION │ Error code from server <https://github.com/ │ Error API Version 1: Server error │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SERVER │ Error code from server <https://github.com/ │ Error API Version 2: Server error │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_GRIDFS │ MONGOC_ERROR_GRIDFS_CHUNK_MISSING │ The GridFS file is missing a │
│ │ │ document in its chunks collection. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_GRIDFS_CORRUPT │ A data inconsistency was detected │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_GRIDFS_INVALID_FILENAME │ You passed a NULL filename to │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_GRIDFS_PROTOCOL_ERROR │ You called │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_GRIDFS_BUCKET_FILE_NOT_FOUND │ A GridFS file is missing from │
│ │ │ files collection. │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_GRIDFS_BUCKET_STREAM │ An error occurred on a stream │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SCRAM │ MONGOC_ERROR_SCRAM_PROTOCOL_ERROR │ Failure in SCRAM-SHA-1 or SCRAM-SHA-256 │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_SERVER_SELECTION │ MONGOC_ERROR_SERVER_SELECTION_FAILURE │ No replica set member or mongos is │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_WRITE_CONCERN │ Error code from server <https://github.com/ │ There was a write concern <> error or │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_TRANSACTION │ MONGOC_ERROR_TRANSACTION_INVALID │ You attempted to start a transaction when │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_CLIENT_SIDE_ENCRYPTION │ Error code produced by libmongocrypt. │ An error occurred in the library │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_AZURE │ MONGOC_ERROR_KMS_SERVER_HTTP │ An Azure HTTP service responded with an │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_KMS_SERVER_BAD_JSON │ An Azure service responded with invalid │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ MONGOC_ERROR_GCP │ MONGOC_ERROR_KMS_SERVER_HTTP │ A GCP HTTP service responded with an │
├─────────────────────────────────────┼──────────────────────────────────────────────┼───────────────────────────────────────────┤
│ │ MONGOC_ERROR_KMS_SERVER_BAD_JSON │ A GCP service responded with invalid JSON │
└─────────────────────────────────────┴──────────────────────────────────────────────┴───────────────────────────────────────────┘
ERROR LABELS
In some cases your application must make decisions based on what category of error the driver has
returned, but these categories do not correspond perfectly to an error domain or code. In such cases,
error labels provide a reliable way to determine how your application should respond to an error.
Any C Driver function that has a bson_t <https://www.mongoc.org/libbson/current/bson_t.html>
out-parameter named reply may include error labels to the reply, in the form of a BSON field named
"errorLabels" containing an array of strings:
{ "errorLabels": [ "TransientTransactionError" ] }
Use mongoc_error_has_label() <> to test if a reply contains a specific label. See
mongoc_client_session_start_transaction() <> for example code that demonstrates the use of error labels
in application logic.
The following error labels are currently defined. Future versions of MongoDB may introduce new labels.
TransientTransactionError
Within a multi-document transaction, certain errors can leave the transaction in an unknown or aborted
state. These include write conflicts, primary stepdowns, and network errors. In response, the application
should abort the transaction and try the same sequence of operations again in a new transaction.
UnknownTransactionCommitResult
When mongoc_client_session_commit_transaction() <> encounters a network error or certain server errors,
it is not known whether the transaction was committed. Applications should attempt to commit the
transaction again until: the commit succeeds, the commit fails with an error not labeled
"UnknownTransactionCommitResult", or the application chooses to give up.
SETTING THE ERROR API VERSION
The driver's error reporting began with a design flaw: when the error domain is MONGOC_ERROR_COLLECTION,
MONGOC_ERROR_QUERY, or MONGOC_ERROR_COMMAND, the error code might originate from the server or the
driver. An application cannot always know where an error originated, and therefore cannot tell what the
code means.
For example, if mongoc_collection_update_one() <> sets the error's domain to MONGOC_ERROR_COLLECTION and
its code to 24, the application cannot know whether 24 is the generic driver error code
MONGOC_ERROR_COLLECTION_UPDATE_FAILED or the specific server error code "LockTimeout".
To fix this flaw while preserving backward compatibility, the C Driver 1.4 introduces "Error API
Versions". Version 1, the default Error API Version, maintains the flawed behavior. Version 2 adds a new
error domain, MONGOC_ERROR_SERVER. In Version 2, error codes originating on the server always have error
domain MONGOC_ERROR_SERVER or MONGOC_ERROR_WRITE_CONCERN. When the driver uses Version 2 the application
can always determine the origin and meaning of error codes. New applications should use Version 2, and
existing applications should be updated to use Version 2 as well.
┌──────────────────────────────────────────────┬────────────────────────────┬────────────────────────────┐
│ Error Source │ API Version 1 │ API Version 2 │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ mongoc_cursor_error() <> │ MONGOC_ERROR_QUERY │ MONGOC_ERROR_SERVER │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ mongoc_client_command_with_opts() │ MONGOC_ERROR_QUERY │ MONGOC_ERROR_SERVER │
│ <>, │ │ │
│ mongoc_database_command_with_opts() │ │ │
│ <>, and other command │ │ │
│ functions │ │ │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ mongoc_client_get_database_names_with_opts() │ MONGOC_ERROR_QUERY │ MONGOC_ERROR_SERVER │
│ <> and other command helper │ │ │
│ functions │ │ │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ mongoc_collection_insert_one() <> │ MONGOC_ERROR_COMMAND │ MONGOC_ERROR_SERVER │
│ mongoc_collection_insert_many() <> │ │ │
│ mongoc_collection_update_one() <> │ │ │
│ mongoc_collection_update_many() <> │ │ │
│ mongoc_collection_replace_one() <> │ │ │
│ mongoc_collection_delete_one() <> │ │ │
│ mongoc_collection_delete_many() <> │ │ │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ mongoc_bulk_operation_execute() <> │ MONGOC_ERROR_COMMAND │ MONGOC_ERROR_SERVER │
├──────────────────────────────────────────────┼────────────────────────────┼────────────────────────────┤
│ Write-concern timeout │ MONGOC_ERROR_WRITE_CONCERN │ MONGOC_ERROR_WRITE_CONCERN │
└──────────────────────────────────────────────┴────────────────────────────┴────────────────────────────┘
The Error API Versions are defined with MONGOC_ERROR_API_VERSION_LEGACY and MONGOC_ERROR_API_VERSION_2.
Set the version with mongoc_client_set_error_api() <> or mongoc_client_pool_set_error_api() <>.
See also:
MongoDB Server Error Codes <https://github.com/mongodb/mongo/blob/master/src/mongo/base/error_codes.yml>
Author
MongoDB, Inc
Copyright
2009-present, MongoDB, Inc.
2.2.0 Nov 26, 2025 MONGOC_ERRORS(3)