Upgrade to Version 2.x

The driver uses strong naming for all driver components. If your application has dependencies that reference multiple .NET/C# Driver versions, you must create binding redirects, as shown in the following example:

<configuration>
    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="MongoDB.Driver"
                                  publicKeyToken="94992a530f44e321"
                                  culture="neutral" />
                <bindingRedirect oldVersion="2.28.0.0"
                                 newVersion="<version number to use>" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="MongoDB.Bson"
                                  publicKeyToken="94992a530f44e321"
                                  culture="neutral" />
                <bindingRedirect oldVersion="2.28.0.0"
                                 newVersion="<version number to use>" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="MongoDB.Driver.Core"
                                  publicKeyToken="94992a530f44e321"
                                  culture="neutral" />
                <bindingRedirect oldVersion="2.28.0.0"
                                 newVersion="<version number to use>" />
            </dependentAssembly>
        </assemblyBinding>
    </runtime>
</configuration>

The driver changes the signature of Render methods in the Atlas Search builders. In previous driver versions, these methods had the following signature:

Render(IBsonSerializer<TDocument> documentSerializer, IBsonSerializerRegistry serializerRegistry);

In version 2.21.0 and later, the Render methods have the following signature:

Render(SearchDefinitionRenderContext<TDocument> renderContext);

The ObjectSerializer only allows deserialization of types that are considered safe. If not specified otherwise, the ObjectSerializer uses the types returned by ObjectSerializer.DefaultAllowedTypes.

To learn more about the ObjectSerializer, visit the FAQ. For more information on DefaultAllowedTypes, visit the API Documentation.

The default LinqProvider has been changed to LINQ3. The LinqProvider can be configured for LINQ2 in MongoClientSettings as shown in the following code example:

var connectionString = "<connection string>";
var clientSettings = MongoClientSettings
   .FromConnectionString(connectionString);
clientSettings.LinqProvider = LinqProvider.V2;
var client = new MongoClient(clientSettings);

If your application uses the LINQ3 provider, you can't use -1 to represent the positional operator when updating an array. To learn how to use the positional operator, see Update One and Update Many.

The driver drops support for MongoDB Server v3.4 and earlier. You must upgrade your MongoDB Server to v3.6 or later.

To learn how to upgrade your MongoDB Server deployment, see Release Notes in the MongoDB Server manual. To learn more about compatibility between the .NET/C# Driver and MongoDB Server, see the Compatibility page.

The driver drops support for .NET framework v4.5.2 and earlier. Your application must use .NET framework v4.7.2 or later, .NET Core 2.x or later, or .NET 5 or later.

To learn more about compatibility between the .NET/C# Driver and .NET, see the Compatibility page.

The driver drops support for .NET Standard v1.5. Your application must use .NET Standard v2.0 or later.