This page is for users who would like to migrate their 1.7 driver to 4.0.
The following sections serve as a quick look at what have been added and/or changed in 4.0 .NET driver.
For more details: [Driver Migration Guide](https://neo4j.com/docs/migration-guide/4.0/upgrade-driver/)
#### What's New

* Upcoming version is now named as 4.0.0 instead of 2.0.0 to better align with server versions.
* Bolt V4.0 is implemented in the 4.0.0 driver.
* Reactive API is available under namespace `Neo4j.Driver.Reactive` when using together with Neo4j 4.0 databases.
* Multi-databases support is added. Database can be selected for each session on creation
  with `SessionConfig#ForDatabase`.
* A new feature detection method `IDriver#SupportsMultiDbAsync` is added for querying if the remote database supports
  multi-databases.
* A new `IDriver#VerifyConnectivityAsync` method is introduced for verify the availability of remote DBMS.

#### Breaking Changes

* Encrypted is turned off by default. When encryption is explicitly enabled, the default trust mode is to trust the
  certificates that are trusted by underlying operating system, and hostname verification is enforced by default.
* v1 is removed from drivers' package name. All public APIs are under the namespace `Neo4j.Driver` instead of the
  old `Neo4j.Driver.V1`.
* The `Neo4j.Driver` package contains only the asynchronous API. Synchronous session API has been moved to the
  namespace `Neo4j.Driver.Simple`.
* A new `neo4j` scheme is added and designed to work with all possible 4.0 server deployments. `bolt` scheme is still
  available for explicit direct connections with a single instance and/or a single member in a cluster. For 3.x
  servers, `neo4j` replaces `bolt+routing`.
* Asynchronous methods have been extracted out and put in interfaces prefixed with `IAsync`, whereas synchronous methods
  are kept under the old interface but live in package `Neo4j.Driver.Simple`. This change ensures that blocking and
  no-blocking APIs can never be mixed together.
* `IDriver#Session` methods now make use of a session option builder rather than method arguments.
* Bookmark has changed from a `string` and/or a list of strings to a `Bookmark` object.
* `ITransaction#Success` is replaced with `ITransaction#Commit`.
  However unlike `ITransaction#Success` which only marks the transaction to be successful and then waits
  for `ITransaction#Dispose` to actually perform the real commit, `ITransaction#Commit` commits the transaction
  immediately.
  Similarly, `ITransaction#Failure` is replaced with `ITransaction#Rollback`. A transaction in 4.0 can only be committed
  OR rolled back once.
  If a transaction is not committed explicitly using `ITransaction#Commit`, `ITransaction#Dispose` will roll back the
  transaction.
* `Statement` has been renamed to `Query`. `IStatementResult` has been simplified to `IResult`.
  Similarly, `IStatementResultCursor` has been renamed to `IResultCursor`.
* A result can only be consumed once. A result is consumed if either the query result has been discarded by
  invoking `IResult#Consume` and/or the outer scope where the result is created, such as a transaction or a session, has
  been closed.
  Attempts to access consumed results will be responded with a `ResultConsumedException`.
* `LoadBalancingStrategy` is removed from `Config` class and the drivers always default to `LeastConnectedStrategy`.
* The `IDriverLogger` has been renamed to `ILogger`.
* `TrustStrategy` is replaced with `TrustManager`.