• What's New

For versions 4.5 and later, refer to the What’s New - Java Sync Documentation.

What’s new in 4.4

  • Compatibility with MongoDB 5.1 and support for Java 17
  • Added support for index hints in an AggregateIterable
  • Added support for the $merge and $out aggregation stages on secondaries
  • Use of the mergeObjects() method in the Updates builder
  • DocumentCodec does not ignore a CodecRegistry when writing to an Iterable or a Map instance

What’s new in 4.3

This release fully supports all MongoDB releases from versions 2.6 to 4.4. It also supports some features of the next release of MongoDB.

New features of the 4.3 Java driver release include:

  • Added support for the MongoDB Versioned API. See the ServerApi API documentation for details.
  • Removed most restrictions on allowed characters in field names of documents being inserted or replaced. This is a behavioral change for any application that is relying on client-side enforcement of these restrictions. In particular:
    • Restrictions on field names containing the “.” character have been removed. This affects all insert and replace operations.
    • Restrictions on field names starting with the “$” character have been removed for all insert operations.
    • Restrictions in nested documents on field names starting with the “$” character have been removed for all replace operations.
    • Restrictions in the top-level document on field names starting with the “$” character remain for all replace operations. This is primarily to prevent accidental use of a replace operation when the intention was to use an update operation.
    • Note that unacknowledged writes using dollar-prefixed or dotted keys may be silently rejected by pre-5.0 servers, where some restrictions on field names are still enforced in the server.
  • Added support for setting Netty io.netty.handler.ssl.SslContext, which may be used as a convenient way to utilize OpenSSL as an alternative to the TLS/SSL protocol implementation in a JDK.
  • Added builders for the new $setWindowFields pipeline stage of an aggregation pipeline.

What’s new in 4.2

This release fully supports all MongoDB releases from versions 2.6 to 4.4. New features of the 4.2 Java driver release include:

  • The Reactive Streams driver now utilizes Project Reactor internally. Project reactor follows the Reactive Streams specification and has greatly simplified the implementation of the driver.
  • Added support for Azure and GCP key stores to client-side field level encryption.
  • Added support for caching Kerberos tickets so that they can be re-used for multiple authentication requests.
  • Added support for constructing legacy com.mongodb.MongoClient instances with MongoClientSettings or ConnectionString as the configuration, instead of MongoClientOptions or MongoClientURI.
  • Added support for explain of find and aggregate commands.
  • Added a JsonObject class to make encoding from and decoding to JSON more efficient by avoiding an intermediate Map representation.
  • Added a BsonRepresentation annotation that allows ObjectId BSON values to be represented as Strings in POJO classes.
  • Added support for the BsonIgnore annotation in Scala case classes.
  • Added a Filters.empty() method.

What’s new in 4.1

This release fully supports all MongoDB releases from versions 2.6 to 4.4. Key new features of the 4.1 Java driver release include:

  • Significant reduction in client-perceived failover times during planned maintenance events
  • Update and delete operations support index hinting.
  • The find operation supports allowDiskUse for sorts that require too much memory to execute in RAM.
  • Authentication supports the MONGODB-AWS mechanism using Amazon Web Services (AWS) Identity and Access Management (IAM) credentials.
  • Authentication requires fewer round trips to the server, resulting in faster connection setup.

What’s new in 4.0

This release adds no new features but, as a major release, contains breaking changes that may affect your application. Please consult the Upgrading Guide for an enumeration of the breaking changes.

What’s new in 3.12

This release fully supports all MongoDB releases from versions 2.6 to 4.2. Key new features of the 3.12 Java driver release include:

Security improvements

Client-side field level encryption is supported. Automatic encryption and decryption is available for users of MongoDB Enterprise Advanced, while explicit encryption and decryption is available for users of MongoDB Community.

See Client-side Encryption for further details.

Improved interoperability when using the native UUID type

The driver now supports setting the BSON binary representation of java.util.UUID instances via a new UuidRepresentation property on MongoClientSettings. The default representation has not changed, but it will in the upcoming 4.0 major release of the driver. Applications that store UUID values in MongoDB can use this setting to easily control the representation in MongoDB without having to register a Codec<Uuid> in the CodecRegistry.

See MongoClientSettings.getUuidRepresentation for details.

What’s new in 3.11

This release fully supports all MongoDB releases from versions 2.6 to 4.2. Key new features of the 3.11 Java driver release include:

Improved transactions support

  • The transactions API supports MongoDB 4.2 distributed transactions for use with sharded clusters. Distributed transactions use the same API as replica set transactions.
  • The sessions API supports the ClientSession.withTransaction() method to conveniently run a transaction with automatic retries and at-most-once semantics.
  • The transactions API supports the maxCommitTime option to control the maximum amount of time to wait for a transaction to commit.

Reliability improvements

  • Most read operations are by default automatically retried. Supported read operations that fail with a retryable error are retried automatically and transparently.
  • Retryable writes are now enabled by default. Supported write operations that fail with a retryable error are retried automatically and transparently, with at-most-once update semantics.
  • DNS SRV records are periodically polled in order to update the mongos proxy list without having to change client configuration or even restart the client application. This feature is particularly useful when used with a sharded cluster on MongoDB Atlas, which dynamically updates SRV records whenever you resize your Atlas sharded cluster.
  • Connections to the replica set primary are no longer closed after a step-down, allowing in progress read operations to complete.

Security improvements

Client-side encryption is supported. Automatic encryption and decryption is available for users of MongoDB Enterprise Advanced, while explicit encryption and decryption is available for users of MongoDB Community.

See Client-side Encryption for further details.

General improvements

  • New aggregate helper methods support running database-level aggregations.
  • Aggregate helper methods now support the $merge pipeline stage, and Aggregates.merge() builder methods support creation of the new pipeline stage.
  • Zstandard for wire protocol compression is supported in addition to Snappy and Zlib.
  • Change stream helpers now support the startAfter option.
  • Index creation helpers now support wildcard indexes.

Full list of changes

What’s new in 3.10

Key new features of the 3.10 Java driver release:

Native asynchronous TLS/SSL support

Previously, any use of our asynchronous drivers with TLS/SSl required the use of Netty. In 3.10, the driver supports asynchronous TLS/SSL natively, so no third-party dependency is required. To accomplish this, the driver contains code vendored from https://github.com/marianobarrios/tls-channel.

Operational improvements

When connecting with the mongodb+srv protocol, the driver now polls DNS for changes to the SRV records when connected to a sharded cluster. See Polling SRV Records for Mongos Discovery for more details.

When retryable writes are enabled, the driver now outputs log messages at DEBUG level when a retryable write is attempted. See JAVA-2964 for more details.

Codec Improvements

The driver now mutates the id property of a POJO, when inserting a document via a POJO with a null id property of type ObjectId. See JAVA-2674 for more details.


The driver now offers a JNDI ObjectFactory implementation for creating instances of com.mongodb.client.MongoClient, the interface introduced in version 3.7 of the driver. See JAVA-2883 for more details.

Full list of changes

What’s new in 3.9

Key new features of the 3.9 Java driver release:

Android support

The mongodb-driver-embedded-android module supports interaction with a MongoDB server running on an Android device. See MongoDB Mobile for more details.


Numerous classes and methods have been deprecated in the 3.9 release in preparation for a major 4.0 release. See the Upgrading Guide for more information.

What’s New in 3.8

Key new features of the 3.8 Java driver release:


The Java driver now provides support for executing CRUD operations within a transaction (requires MongoDB 4.0). See the Transactions and MongoDB Drivers section of the documentation and select the Java (Sync) tab.

Change Stream enhancements

The Java driver now provides support for opening a change stream against an entire database, via new MongoDatabase.watch methods, or an entire deployment, via new MongoClient.watch methods. See Change Streams for further details.

SCRAM-256 Authentication Mechanism

The Java driver now provides support for the SCRAM-256 authentication mechanism (requires MongoDB 4.0).

What’s New in 3.7

Key new features of the 3.7 Java driver release:

Java 9 support


The Java driver now provides a set of JAR files that are compliant with the Java 9 module specification, and Automatic-Module-Name declarations have been added to the manifests of those JAR files. See the Installation Guide for information on which JAR files are now Java 9-compliant modules as well as what each of their module names is.

Note that it was not possible to modularize all the existing JAR files due to the fact that, for some of them, packages are split amongst multiple JAR files, and this violates a core rule of the Java 9 module system which states that at most one module contains classes for any given package. For instance, the mongodb-driver and mongodb-driver-core JAR files both contain classes in the com.mongodb package, and thus it’s not possible to make both mongodb-driver and mongodb-driver-core Java 9 modules. Also so-called “uber jars” like mongo-java-driver are not appropriate for Java 9 modularization, as they can conflict with their non-uber brethren, and thus have not been given module names.

Note that none of the modular JAR files contain module-info class files yet. Addition of these classes will be considered in a future release.

New Entry Point

So that the driver can offer a modular option, a new entry point has been added to the com.mongodb.client package. Static methods in this entry point, com.mongodb.client.MongoClients, returns instances of a new com.mongodb.client.MongoClient interface. This interface, while similar to the existing com.mongodb.MongoClient class in that it is a factory for com.mongodb.client.MongoDatabase instances, does not support the legacy com.mongodb.DBCollection-based API, and thus does not suffer from the aforementioned package-splitting issue that prevents Java 9 modularization. This new entry point is encapsulated in the new mongodb-driver-sync JAR file, which is also a Java 9-compliant module.

The new entry point also moves the driver further in the direction of effective deprecation of the legacy API, which is now only available only via the mongo-java-driver and mongodb-driver uber-jars, which are not Java 9 modules. At this point there are no plans to offer the legacy API as a Java 9 module.

See Connect To MongoDB for details on the new com.mongodb.client.MongoClients and how it compares to the existing com.mongodb.MongoClient class.

Unix domain socket support

The 3.7 driver adds support for Unix domain sockets via the jnr.unixsocket library. Connecting to Unix domain sockets is done via the ConnectionString or via UnixServerAddress.

PojoCodec improvements

The 3.7 release brings support for Map<String, Object> to the POJO Codec.

JSR-310 Instant, LocalDate & LocalDateTime support

Support for Instant, LocalDate and LocalDateTime has been added to the driver. The MongoDB Java drivers team would like to thank Cezary Bartosiak for their excellent contribution to the driver. Users needing alternative data structures and / or more flexibility regarding JSR-310 dates should check out the alternative JSR-310 codecs provider by Cezary: bson-codecs-jsr310.

JSR-305 NonNull annotations

The public API is now annotated with JSR-305 compatible @NonNull and @Nullable annotations. This will allow programmers to rely on tools like FindBugs/SpotBugs, IDEs like IntelliJ IDEA, and compilers like the Kotlin compiler to find errors in the use of the driver via static analysis rather than via runtime failures.

Improved logging of commands

When the log level is set to DEBUG for the org.mongodb.driver.protocol.command logger, the driver now logs additional information to aid in debugging:

  • Before sending the command, it logs the full command (up to 1000 characters), and the request id.
  • After receive a response to the command, it logs the request id and elapsed time in milliseconds.

Here’s an example

10:37:29.099 [cluster-ClusterId {value='5a466138741fc252712a6d71', description='null'}-] DEBUG org.mongodb.driver.protocol.command -
Sending command '{ "hello" : 1, "$db" : "admin" } ...' with request id 4 to database admin on connection [connectionId{localValue:1, serverValue:1958}] to server
10:37:29.104 [cluster-ClusterId{value='5a466138741fc252712a6d71', description='null'}-] DEBUG org.mongodb.driver.protocol.command -
Execution of command with request id 4 completed successfully in 22.44 ms on connection [connectionId {localValue:1, serverValue:1958}] to server

Improved support for “raw” documents

When working with “raw” BSON for improved performance via the RawBsonDocument, the efficiency of accessing embedded documents and arrays has been drastically improved by returning raw slices of the containing document or array. For instance

RawBsonDocument doc = new RawBsonDocument(bytes);

// returns a RawBsonDocument that is a slice of the bytes from the containing doc
BsonDocument embeddedDoc = doc.getDocument("embeddedDoc");

// returns a RawBsonArray that is a slice of the bytes from the containing doc
BsonArray embeddedArray = doc.getArray("embeddedArray");

// returns a RawBsonDocument that is a slice of the bytes from the containing array
BsonDocument embeddedDoc2 = (BsonDocument) embeddedArray.get(0);

What’s New in 3.6

Key new features of the 3.6 Java driver release:

Change Stream support

The 3.6 release adds support for change streams.

Retryable writes

The 3.6 release adds support for retryable writes using the retryWrites option in MongoClientOptions.


The 3.6 release adds support for compression of messages to and from appropriately configured MongoDB servers:

Causal consistency

The 3.6 release adds support for causally consistency via the new ClientSession API.

Application-configured server selection

The 3.6 release adds support for application-configured control over server selection, using the serverSelector option in MongoClientOptions.

POJO Codec improvements

The 3.6 release brings new improvements to the POJO Codec:

  • Improved sub-class and discriminator support.
  • Support for custom Collection and Map implementations.
  • Improvements to the BsonCreator annotation, which now supports @BsonId and @BsonProperty with values that represent the read name of the property.
  • A new PropertyCodecProvider API, allowing for easy and type-safe handling of container types.
  • Added the SET_PRIVATE_FIELDS_CONVENTION convention.
  • Added the USE_GETTERS_FOR_SETTERS convention.

The MongoDB Java drivers team would like to thank both Joseph Florencio and Qi Liu for their excellent contributions to the PojoCodec.

What’s New in 3.5

Key new features of the 3.5 Java driver release:

Native POJO support

The 3.5 release adds support for POJO serialization at the BSON layer, and can be used by the synchronous and asynchronous drivers. See the POJO Quick start pages for details.

Improved JSON support

The 3.5 release improves support for JSON parsing and generation.

  • Implements the new Extended JSON specification
  • Implements custom JSON converters to give applications full control over JSON generation for each BSON type

See the JSON reference for details.

Connection pool monitoring

The 3.5 release adds support for monitoring connection pool-related events.

SSLContext configuration

The 3.5 release supports overriding the default javax.net.ssl.SSLContext used for SSL connections to MongoDB.

KeepAlive configuration deprecated

The 3.5 release deprecated socket keep-alive settings, also socket keep-alive checks are now on by default. It is strongly recommended that system keep-alive settings should be configured with shorter timeouts.

See the ‘does TCP keep-alive time affect MongoDB deployments?’ documentation for more information.

What’s New in 3.4

The 3.4 release includes full support for the MongoDB 3.4 server release. Key new features include:

Support for Decimal128 Format

import org.bson.types.Decimal128;

The Decimal128 format supports numbers with up to 34 decimal digits (i.e. significant digits) and an exponent range of −6143 to +6144.

To create a Decimal128 number, you can use

Support for Collation

import com.mongodb.client.model.Collation;

Collation allows users to specify language-specific rules for string comparison. Use the Collation.builder() to create the Collation object. For example, the following example creates a Collation object with Primary level of comparison and locale fr.


You can specify collation at the collection level, at an index level, or at a collation-supported operation level:

Collection Level

To specify collation at the collection level, pass a Collation object as an option to the createCollection() method. To specify options to the createCollection method, use the CreateCollectionOptions class.

database.createCollection("myColl", new CreateCollectionOptions().collation(

Index Level

To specify collation for an index, pass a Collation object as an option to the createIndex() method. To specify index options, use the IndexOptions class.

IndexOptions collationIndexOptions = new IndexOptions().name("collation-fr")

        Indexes.ascending("name"), collationIndexOptions);

Operation Level

The following operations support collation by specifying the Collation object to their respective Iterable object.

  • MongoCollection.aggregate()

  • MongoCollection.distinct()

  • MongoCollection.find()

  • MongoCollection.mapReduce()

For example:

Collation collation = Collation.builder()

collection.find(Filters.eq("category", "cafe")).collation(collation);

                         Aggregates.group("$category", Accumulators.sum("count", 1))))

The following operations support collation by specifying the Collation object as an option using the corresponding option class for the method:

  • MongoCollection.count()
  • MongoCollection.deleteOne()
  • MongoCollection.deleteMany()
  • MongoCollection.findOneAndDelete()
  • MongoCollection.findOneAndReplace()
  • MongoCollection.findOneAndUpdate()
  • MongoCollection.updateOne()
  • MongoCollection.updateMany()
  • MongoCollection.bulkWrite() for:

    • DeleteManyModel and DeleteOneModel using DeleteOptions to specify the collation
    • ReplaceOneModel, UpdateManyModel, and UpdateOneModel using UpdateOptions to specify the collation.

For example:

Collation collation = Collation.builder()

collection.count(Filters.eq("category", "cafe"), new CountOptions().collation(collation));

collection.updateOne(Filters.eq("category", "cafe"), set("stars", 1),
                     new UpdateOptions().collation(collation));

                new UpdateOneModel<>(new Document("category", "cafe"),
                                     new Document("$set", new Document("x", 0)),
                                     new UpdateOptions().collation(collation)),
                new DeleteOneModel<>(new Document("category", "cafe"),
                                     new DeleteOptions().collation(collation))));

For more information on collation, including the supported locales, refer to the manual.

Other MongoDB 3.4 features

Support for JNDI

The synchronous driver now includes a JNDI ObjectFactory implementation.


See the upgrading guide on how to upgrade to 3.5.