Rebus 8 - Rebus.Subscriptions.ISubscriptionStorage, but a primary registration already exists

Question

I'm trying to upgrade from Rebus 7 to Rebus 8, and got this exception:

System.InvalidOperationException: Attempted to register primary -> Rebus.Subscriptions.ISubscriptionStorage, but a primary registration already exists: primary -> Rebus.Subscriptions.ISubscriptionStorage
   at Rebus.Injection.Injectionist.Register[TService](Func`2 resolverMethod, Boolean isDecorator, String description)
   at Rebus.Injection.Injectionist.Register[TService](Func`2 resolverMethod, String description)
   at Rebus.Config.StandardConfigurer`1.Register(Func`2 factoryMethod, String description)
   at Rebus.Config.PostgreSqlConfigurationExtensions.StoreInPostgres(StandardConfigurer`1 configurer, IPostgresConnectionProvider connectionProvider, String tableName, Boolean isCentralized, Boolean automaticallyCreateTables, String schemaName)
   at Rebus.Config.PostgreSqlConfigurationExtensions.StoreInPostgres(StandardConfigurer`1 configurer, String connectionString, String tableName, Boolean isCentralized, Boolean automaticallyCreateTables, Action`1 additionalConnectionSetup)   

I have my subscriptions saved in posgres DB, and if I comment out the call StandardConfigurer<ISubscriptionStorage>.StoreInPostgres(...) it all works ok, but without subscriptions.

Answer 1

The error message means that another subscription storage has already been registered.

This would be case if you were using e.g. Azure Service Bus (which has native support for pub/sub messaging, so the transport registers itself as the subscription manager).

BUT since the error came when upgrading from Rebus 7 to Rebus 8, and the big difference between those two versions is that the in-mem transport from v8 also registers itself as a subscription storage (i.e. it works as a transport that has native support for pub/sub), my guess is that that's why there's already a registration... if that's the case, and you still want to use Postgres for subscriptions, the solution is to configure the in-mem transport like this:

services.AddRebus(
    configure => configure
        .Transport(t => t.UseInMemoryTransport(network, "my-queue", registerSubscriptionStorage: false))
);