# Assembly Scanning Changes in NServiceBus Version 6


## Nested directories not scanned by default

The default behavior of version 6 is to not scan nested directories for assemblies. This behavior can be re-enabled using the [assembly scanning API](/nservicebus/hosting/assembly-scanning.md#assembly-files-nested-directories).


## Scanning uses an "exclude" approach

The API has been changed to an "exclude a list" approach. See [Assemblies to scan](/nservicebus/hosting/assembly-scanning.md#assemblies-to-scan) for more information.

```csharp
// For NServiceBus version 6.x
var scanner = endpointConfiguration.AssemblyScanner();
scanner.ExcludeAssemblies(
    "BadAssembly1.dll",
    "BadAssembly2.dll");

// For NServiceBus version 5.x
var excludesBuilder =
    AllAssemblies.Matching("NServiceBus")
        .And("MyCompany.")
        .Except("BadAssembly1.dll")
        .And("BadAssembly2.dll");
busConfiguration.AssembliesToScan(excludesBuilder);
```