MongoDB NodeJS Driver 6.0.0 Released

6.0.0 (2023-08-22)

The MongoDB Node.js team is pleased to announce version 6.0.0 of the mongodb package!

The main focus of this release was usability improvements and a streamlined API. Read on for details!

Release Notes

This is a list of changes relative to v5.8.1 of the driver. ALL changes listed below are BREAKING.
Users migrating from an older version of the driver are advised to upgrade to at least v5.8.1 before adopting v6.

:hammer_and_wrench: Runtime and dependency updates

Minimum Node.js version is now v16.20.1

The minimum supported Node.js version is now v16.20.1. We strive to keep our minimum supported Node.js version in sync with the runtime’s release cadence to keep up with the latest security updates and modern language features.

BSON version 6.0.0

This driver version has been updated to use bson@6.0.0. BSON functionality re-exported from the driver is subject to the changes outlined in the BSON V6 release notes.

Optional peer dependency version bumps

  • kerberos optional peer dependency minimum version raised to 2.0.1, dropped support for 1.x
  • zstd optional peer depedency minimum version raised to 1.1.0 from 1.0.0
  • mongodb-client-encryption optional peer dependency minimum version raised to 6.0.0 from 2.3.0 (note that mongodb-client-encryption does not have 3.x-5.x version releases)

As of version 6.0.0, all useful public APIs formerly exposed from mongodb-client-encryption have been moved into the driver and should now be imported directly from the driver. These APIs rely internally on the functionality exposed from mongodb-client-encryption, but there is no longer any need to explicitly reference mongodb-client-encryption in your application code.

Allow socks to be installed optionally

The driver uses the socks dependency to connect to mongod or mongos through a SOCKS5 proxy. socks used to be a required dependency of the driver and was installed automatically. Now, socks is a peerDependency that must be installed to enable socks proxy support.

:sunny: API usability improvements

findOneAndX family of methods will now return only the found document or null by default (includeResultMetadata is false by default)

Previously, the default return type of this family of methods was a ModifyResult containing the found document and additional metadata. This additional metadata is unnecessary for the majority of use cases, so now, by default, they will return only the found document or null.

The previous behavior is still available by explicitly setting includeResultMetadata: true in the options.

See the following blog post for more information.

// This has the same behaviour as providing `{ includeResultMetadata: false }` in the v5.7.0+ driver
await collection.findOneAndUpdate({ hello: 'world' }, { $set: { hello: 'WORLD' } });
// > { _id: new ObjectId("64c4204517f785be30795c92"), hello: 'world' }

// This has the same behaviour as providing no options in any previous version of the driver
await collection.findOneAndUpdate(
  { hello: 'world' },
  { $set: { hello: 'WORLD' } },
  { includeResultMetadata: true }
// > {
// >  lastErrorObject: { n: 1, updatedExisting: true },
// >  value: { _id: new ObjectId("64c4208b17f785be30795c93"), hello: 'world' },
// >  ok: 1
// > }

session.commitTransaction() and session.abortTransaction() return void

Each of these methods erroneously returned server command results that can be different depending on server version or type the driver is connected to. These methods return a promise that if resolved means the command (aborting or commiting) sucessfully completed and rejects otherwise. Viewing command responses is possible through the command monitoring APIs on the MongoClient.

withSession and withTransaction return the value returned by the provided function

The await client.withSession(async session => {}) now returns the value that the provided function returns. Previously, this function returned void this is a feature to align with the following breaking change.

The await session.withTransaction(async () => {}) method now returns the value that the provided function returns. Previously, this function returned the server command response which is subject to change depending on the server version or type the driver is connected to. The return value got in the way of writing robust, reliable, consistent code no matter the backing database supporting the application.

When upgrading to this version of the driver, be sure to audit any usages of withTransaction for if statements or other conditional checks on the return value of withTransaction. Previously, the return value was the command response if the transaction was committed and undefined if it had been manually aborted. It would only throw if an operation or the author of the function threw an error. Since prior to this release it was not possible to get the result of the function passed to withTransaction we suspect most existing functions passed to this method return void, making withTransaction a void returning function in this major release. Take care to ensure that the return values of your function match the expectation of the code that follows the completion of withTransaction.

Driver methods throw if a session is provided from a different MongoClient

Providing a session from one MongoClient to a method on a different MongoClient has never been a supported use case and leads to undefined behavior. To prevent this mistake, the driver now throws a MongoInvalidArgumentError if session is provided to a driver helper from a different MongoClient.

// pre v6
const session = client1.startSession();
client2.db('foo').collection('bar').insertOne({ name: 'john doe' }, { session }); // no error thrown, undefined behavior

// v6+
const session = client1.startSession();
client2.db('foo').collection('bar').insertOne({ name: 'john doe' }, { session });
// MongoInvalidArgumentError thrown

Callbacks removed from ClientEncryption’s encrypt, decrypt, and createDataKey methods

Driver v5 dropped support for callbacks in asynchronous functions in favor of returning promises in order to provide more consistent type and API experience. In alignment with that, we are now removing support for callbacks from the ClientEncryption class.

MongoCryptError is now a subclass of MongoError

Since MongoCryptError made use of Node.js 16’s Error API, it has long supported setting the Error.cause field using options passed in via the constructor. Now that Node.js 16 is our minimum supported version, MongoError has been modified to make use of this API as well, allowing us to let MongoCryptError subclass from it directly.

:gear: Option parsing improvements

useNewUrlParser and useUnifiedTopology emit deprecation warnings

These options were removed in 4.0.0 but continued to be parsed and silently left unused. We have now added a deprecation warning through Node.js’ warning system and will fully remove these options in the next major release.

Boolean options only accept ‘true’ or ‘false’ in connection strings

Prior to this change, we accepted the values '1', 'y', 'yes', 't' as synonyms for true and '-1', '0', 'f', 'n', 'no' as synonyms for false. These have now been removed in an effort to make working with connection string options simpler.

// Incorrect
const client = new MongoClient('mongodb://localhost:27017?tls=1'); // throws MongoParseError

// Correct
const client = new MongoClient('mongodb://localhost:27017?tls=true');

Repeated options are no longer allowed in connection strings

In order to avoid accidental misconfiguration the driver will no longer prioritize the first instance of an option provided on the URI. Instead repeated options that are not permitted to be repeated will throw an error.

This change will ensure that connection strings that contain options like tls=true&tls=false are no longer ambiguous.

TLS certificate authority and certificate-key files are now read asynchronously

In order to align with Node.js best practices of keeping I/O async, we have updated the MongoClient to store the file names provided to the existing tlsCAFile and tlsCertificateKeyFile options, as well as the tlsCRLFile option, and only read these files the first time it connects. Prior to this change, the files were read synchronously on MongoClient construction.

This has no effect on driver functionality when TLS configuration files are properly specified. However, if there are any issues with the TLS configuration files (invalid file name), the error is now thrown when the MongoClient is connected instead of at construction time.

const client = new MongoClient(CONNECTION_STRING, {
  tls: true,
  tlsCAFile: 'caFileName',
  tlsCertificateKeyFile: 'certKeyFile',
  tlsCRLFile: 'crlPemFile'
}); // Files are not read here, but file names are stored on the MongoClient

await client.connect(); // Files are now read and their contents stored
await client.close();

await client.connect(); // Since the file contents have already been cached, the files will not be read again.

Take a look at our TLS documentation for more information on the tlsCAFile, tlsCertificateKeyFile, and tlsCRLFile options.

:bug: Bug fixes

db.command() and admin.command() unsupported options removed

These APIs allow for specifying a command BSON document directly, so the driver does not try to enumerate all possible commands that could be passed to this API in an effort to be as forward and backward compatible as possible.

The db.command() and admin.command() APIs have their options types updated to accurately reflect options compatible on all commands that could be passed to either API.

Perhaps most notably, readConcern and writeConcern options are no longer handled by the driver. Users must attach these properties to the command that is passed to the .command() method.

Removed irrelevant fields from ConnectionPoolCreatedEvent.options

The options field of ConnectionPoolCreatedEvent now has the following shape:

	maxPoolSize: number,
	minPoolSize: number,
	maxConnecting: number,
	maxIdleTimeMS: number,
	waitQueueTimeoutMS: number

Fixed parsing of empty readPreferenceTags in connection string

The following connection string will now produce the following readPreferenceTags:

// client.options.readPreference.tags
[{ region: 'ny' }, { rack: 'r1' }, {}];

The empty readPreferenceTags allows drivers to still select a server if the leading tag conditions are not met.

Corrected GridFSBucketWriteStream’s Writable method overrides and event emission

Our implementation of a writeable stream for GridFSBucketWriteStream mistakenly overrode the write() and end() methods, as well as, manually emitted 'close', 'drain', 'finish' events. Per Node.js documentation, these methods and events are intended for the Node.js stream implementation to provide, and an author of a stream implementation is supposed to override _write, _final, and allow Node.js to manage event emitting.

Since the API is still a Writable stream most usages will continue to work with no changes, the .write() and .end() methods are still available and take the same arguments. The breaking change relates to the improper manually emitted event listeners that are now handled by Node.js. The 'finish' and 'drain' events will no longer receive the GridFSFile document as an argument (this is the document inserted to the bucket’s files collection after all chunks have been inserted). Instead, it will be available on the stream itself as a property: gridFSFile.

// If our event handler is declared as a `function` "this" is bound to the stream.
  .on('finish', function () {

// If our event handler is declared using big arrow notation,
// the property is accessible on a scoped variable
const uploadStream = bucket.openUploadStream('file.txt');
  .on('finish', () => console.log(uploadStream.gridFSFile));

Since the class no longer emits its own events: static constants GridFSBucketWriteStream.ERROR, GridFSBucketWriteStream.FINISH, GridFSBucketWriteStream.CLOSE have been removed to avoid confusion about the source of the events and the arguments their listeners accept.

Fix manually emitted events from GridFSBucketReadStream

The GridFSBucketReadStream internals have also been corrected to no longer emit events that are handled by Node’s stream logic. Since the class no longer emits its own events: static constants GridFSBucketReadStream.ERROR, GridFSBucketReadStream.DATA, GridFSBucketReadStream.CLOSE, and GridFSBucketReadStream.END have been removed to avoid confusion about the source of the events and the arguments their listeners accept.

createDataKey return type fix

Previously, the TypeScript for createDataKey incorrectly declared the result to be a DataKey but the method actually returns the DataKey’s insertedId.

:scroll: Removal of deprecated functionality

db.addUser() and admin.addUser() removed

The deprecated addUser APIs have been removed. The driver maintains support across many server versions and the createUser command has support for different features based on the server’s version. Since applications can generally write code to work against a uniform and perhaps more modern server, the path forward is for applications to send the createUser command directly.

The associated options interface with this API has also been removed: AddUserOptions.

See the createUser documentation for more information.

const db = client.db('admin');
// Example addUser usage
await db.addUser('myUsername', 'myPassword', { roles: [{ role: 'readWrite', db: 'mflix' }] });
// Example equivalent command usage
await db.command({
  createUser: 'myUsername',
  pwd: 'myPassword',
  roles: [{ role: 'readWrite', db: 'mflix' }]

collection.stats() removed

The collStats command is deprecated starting in server v6.2 so the driver is removing its bespoke helper in this major release. The collStats command is still available to run manually via await db.command(). However, the recommended migration is to use the $collStats aggregation stage.

The following interfaces associated with this API have also been removed: CollStatsOptions and WiredTigerData.

BulkWriteResult deprecated properties removed

The following deprecated properties have been removed as they duplicated those outlined in the [MongoDB CRUD specification|]. The list indicates what properties provide the correct migration:

  • BulkWriteResult.nInsertedBulkWriteResult.insertedCount
  • BulkWriteResult.nUpsertedBulkWriteResult.upsertedCount
  • BulkWriteResult.nMatchedBulkWriteResult.matchedCount
  • BulkWriteResult.nModifiedBulkWriteResult.modifiedCount
  • BulkWriteResult.nRemovedBulkWriteResult.deletedCount
  • BulkWriteResult.getUpsertedIdsBulkWriteResult.upsertedIds / BulkWriteResult.getUpsertedIdAt(index: number)
  • BulkWriteResult.getInsertedIdsBulkWriteResult.insertedIds

Deprecated SSL options have been removed

The following options have been removed with their supported counterparts listed after the →

  • sslCAtlsCAFile
  • sslCRLtlsCRLFile
  • sslCerttlsCertificateKeyFile
  • sslKeytlsCertificateKeyFile
  • sslPasstlsCertificateKeyFilePassword
  • sslValidatetlsAllowInvalidCertificates
  • tlsCertificateFiletlsCertificateKeyFile

The deprecated keepAlive and keepAliveInitialDelay options have been removed

TCP keep alive will always be on and now set to a value of 30000ms.

:wastebasket: Removal of “dead” code

The removed functionality listed in this section was either unused or not useful outside the driver internals.

Constructors for MongoError and its subclasses now clearly indicate they are meant for internal use only

MongoError and its subclasses are not meant to be constructed by users as they are thrown within the driver on specific error conditions to allow users to react to these conditions in ways which match their use cases. The constructors for these types are now subject to change outside of major versions and their API documentation has been updated to reflect this.

AutoEncrypter and MongoClient.autoEncrypter are now internal

As of this release, users will no longer be able to access the AutoEncrypter interface or the MongoClient.autoEncrypter field of an encrypted MongoClient instance as they do not have a use outside the driver internals.

ClientEncryption.onKMSProvidersRefresh function removed

ClientEncryption.onKMSProvidersRefresh was added as a public API in version 2.3.0 of mongodb-client-encryption to allow for automatic refresh of KMS provider credentials. Subsequently, we added the capability to automatically refresh KMS credentials using the KMS provider’s preferred refresh mechanism, and onKMSProviderRefresh is no longer used.

EvalOptions removed

This cleans up some dead code in the sense that there were no eval command related APIs but the EvalOptions type was public, so we want to ensure there are no surprises now that this type has been removed.


  • NODE-5584: adopt bson v6 and mongodb-client-encryption v6 (#3845)
  • NODE-5484: mark MongoError for internal use and remove Node14 cause assignment logic (#3800)
  • NODE-4788: use implementer Writable methods for GridFSBucketWriteStream (#3808)
  • NODE-4986: remove callbacks from ClientEncryption encrypt, decrypt, and createDataKey (#3797)
  • NODE-5490: bump kerberos compatibility to ^2.0.1 (#3798)
  • NODE-3568: ensure includeResultsMetadata is false by default (#3786)
  • NODE-3989: only accept true and false for boolean options (#3791)
  • NODE-5233: prevent session from one client from being used on another (#3790)
  • NODE-5444: emit deprecation warning for useNewUrlParser and useUnifiedTopology (#3792)
  • NODE-5470: convert remaining FLE to TS and drop support for onKMSProvidersRefresh (#3787)
  • NODE-5508: remove EvalOperation and EvalOptions (#3795)
  • NODE-3920: validate options are not repeated in connection string (#3788)
  • NODE-3924: read tls files async (#3776)
  • NODE-5430: make AutoEncrypter and MongoClient.autoEncrypter internal (#3789)
  • NODE-4961: remove command result from commit and abort transaction APIs (#3784)
  • NODE-2014: return executor result from withSession and withTransaction (#3783)
  • NODE-5409: allow socks to be installed optionally (#3782)
  • NODE-4796: remove addUser and collection.stats APIs (#3781)
  • NODE-4936: remove unsupported options from db.command and admin.command (#3775)
  • NODE-5228: remove unneeded fields from ConnectionPoolCreatedEvent.options (#3772)
  • NODE-5190: remove deprecated keep alive options (#3771)
  • NODE-5186: remove duplicate BulkWriteResult accessors (#3766)
  • NODE-5376: remove deprecated ssl options (#3755)
  • NODE-5415: bump minimum Node.js version to v16.20.1 (#3760)


We invite you to try the mongodb library immediately, and report any issues to the NODE project.


Seems like a defect was shipped. MacOS 12.6.8 - the following error prevents any functionality

        options.includeResultMetadata ??= false;

SyntaxError: Unexpected token '??='
    at wrapSafe (internal/modules/cjs/loader.js:984:16)
    at Module._compile (internal/modules/cjs/loader.js:1032:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10)
    at Module.load (internal/modules/cjs/loader.js:933:32)
    at Function.Module._load (internal/modules/cjs/loader.js:774:14)
    at Module.require (internal/modules/cjs/loader.js:957:19)
    at require (internal/modules/cjs/helpers.js:88:18)
    at Object.<anonymous> (/Users/mikestorey/source/learn/mongo-developer/node_modules/mongodb/lib/collection.js:21:27)
    at Module._compile (internal/modules/cjs/loader.js:1068:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10)

Hi @Mike_Storey, what Node.js version are you using? That token is the nullish coalescing assignment operator. Node.js added support for it in v15.0.0 and our lowest supported Node.js version for v6 of the Node Driver is v16.20.1.

Duoh - yep that was it! Got wrapped around the axle on this one. Maybe create something that is indexed by google with that error, I did a lot of searching and came up empty.

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