Message serialization with System.Text.Json is bundled into NServiceBus version 8.1 and above. The built-in serializer is fully compatible with the community-created NServiceBus.Json package.
First, upgrade to NServiceBus 8.1.0 or newer.
Then, instead of:
var serialization = endpointConfiguration.UseSerialization<NServiceBus.Json.SystemJsonSerializer>();
Remove the reference to the NServiceBus.Json NuGet package and use:
var serialization = endpointConfiguration.UseSerialization<NServiceBus.SystemJsonSerializer>();
If full namespaces are not used, this code change may not be necessary, and instead, the
using NServiceBus. statement can be removed.
ContentTypeKey(. method has been renamed to
The low level
WriterOptions(. is no longer available and it's recommended to use the JsonSerializerOptions to control serialization and deserialization behavior.