Akka.NET v1.5.0-alpha1 is a major release that contains a lot of code improvement and rewrites/refactors. **Major upgrades to Akka.Cluster.Sharding in particular**. __Deprecation__ Some codes and packages are being deprecated in v1.5 [Deprecated/removed Akka.DI package](https://github.com/akkadotnet/akka.net/pull/6003) Please use the new `Akka.DependencyInjection` NuGet package as a replacement. Documentation can be read [here](https://getakka.net/articles/actors/dependency-injection.html) [Deprecated/removed Akka.MultiNodeTestRunner package](https://github.com/akkadotnet/akka.net/pull/6002) Please use the new `Akka.MultiNode.TestAdapter` NuGet package as a replacement. Documentation can be read [here](https://getakka.net/articles/testing/multi-node-testing.html). [Streams] [Refactor `SetHandler(Inlet, Outlet, IanAndOutGraphStageLogic)` to `SetHandlers()`](https://github.com/akkadotnet/akka.net/pull/5931) __Changes__ __Akka__ [Add dual targetting to support .NET 6.0](https://github.com/akkadotnet/akka.net/pull/5926) All `Akka.NET` packages are now dual targetting netstandard2.0 and net6.0 platforms, we will be integrating .NET 6.0 better performing API and SDK in the future. [Add `IThreadPoolWorkItem` support to `ThreadPoolDispatcher`](https://github.com/akkadotnet/akka.net/pull/5943) [Add `ValueTask` support to `PipeTo` extensions](https://github.com/akkadotnet/akka.net/pull/6025) [Add `CancellationToken` support to `Cancelable`](https://github.com/akkadotnet/akka.net/pull/6032) [Fix long starting loggers crashing `ActorSystem` startup](https://github.com/akkadotnet/akka.net/pull/6053) All loggers are asynchronously started during `ActorSystem` startup. A warning will be logged if a logger does not respond within the prescribed `akka.logger-startup-timeout` period and will be awaited upon in a detached task until the `ActorSystem` is shut down. This have a side effect in that slow starting loggers might not be able to capture all log events emmited by the `EventBus` until it is ready. __Akka.Cluster__ [Fix `ChannelTaskScheduler` to work with Akka.Cluster, ported from 1.4](https://github.com/akkadotnet/akka.net/pull/5920) [Harden `Cluster.JoinAsync()` and `Cluster.JoinSeedNodesAsync()` methods](https://github.com/akkadotnet/akka.net/pull/6033) [Fix `ShardedDaemonProcess` should use lease, if configured](https://github.com/akkadotnet/akka.net/pull/6058) [Make `SplitBrainResolver` more tolerant to invalid node records](https://github.com/akkadotnet/akka.net/pull/6064) [Enable `Heartbeat` and `HearbeatRsp` message serialization and deserialization](https://github.com/akkadotnet/akka.net/pull/6063) By default, `Akka.Cluster` will now use the new `Heartbeat` and `HartbeatRsp` message serialization/deserialization that was introduced in version 1.4.19. If you're doing a rolling upgrade from a version older than 1.4.19, you will need to set `akka.cluster.use-legacy-heartbeat-message` to true. __Akka.Cluster.Sharding__ [Make Cluster.Sharding recovery more tolerant against corrupted persistence data](https://github.com/akkadotnet/akka.net/pull/5978) [Major reorganization to Akka.Cluster.Sharding](https://github.com/akkadotnet/akka.net/pull/5857) The Akka.Cluster.Sharding changes in Akka.NET v1.5 are significant, but backwards compatible with v1.4 and upgrades should happen seamlessly. Akka.Cluster.Sharding's `state-store-mode` has been split into two parts: CoordinatorStore ShardStore Which can use different persistent mode configured via `akka.cluster.sharding.state-store-mode` & `akka.cluster.sharding.remember-entities-store`. Possible combinations: state-store-mode | remember-entities-store | CoordinatorStore mode | ShardStore mode ------------------ | ------------------------- | ------------------------ | ------------------ persistence (default) | - (ignored) | persistence | persistence ddata | ddata | ddata | ddata ddata | eventsourced (new) | ddata | persistence There should be no breaking changes from user perspective. Only some internal messages/objects were moved. There should be no change in the `PersistentId` behavior and default persistent configuration (`akka.cluster.sharding.state-store-mode`) This change is designed to speed up the performance of Akka.Cluster.Sharding coordinator recovery by moving `remember-entities` recovery into separate actors - this also solves major performance problems with the `ddata` recovery mode overall. The recommended settings for maximum ease-of-use for Akka.Cluster.Sharding going forward will be: ``` akka.cluster.sharding{ state-store-mode = ddata remember-entities-store = eventsourced } ``` However, for the sake of backwards compatibility the Akka.Cluster.Sharding defaults have been left as-is: ``` akka.cluster.sharding{ state-store-mode = persistence # remember-entities-store (not set - also uses legacy Akka.Persistence) } ``` Switching over to using `remember-entities-store = eventsourced` will cause an initial migration of data from the `ShardCoordinator`'s journal into separate event journals going forward - __this migration is irreversible__ without taking the cluster offline and deleting all Akka.Cluster.Sharding-related data from Akka.Persistence, so plan accordingly. __Akka.Cluster.Tools__ [Add typed `ClusterSingleton` support](https://github.com/akkadotnet/akka.net/pull/6050) [Singleton can use `Member.AppVersion` metadata to decide its host node during hand-over](https://github.com/akkadotnet/akka.net/pull/6065) `Akka.Cluster.Singleton` can use `Member.AppVersion` metadata when it is relocating the singleton instance. When turned on, new singleton instance will be created on the oldest node in the cluster with the highest `AppVersion` number. You can opt-in to this behavior by setting `akka.cluster.singleton.consider-app-version` to true. __Akka.Persistence.Query__ [Add `TimeBasedUuid` offset property](https://github.com/akkadotnet/akka.net/pull/5995) __Akka.Remote__ [Fix typo in HOCON SSL settings. Backward compatible with the old setting names](https://github.com/akkadotnet/akka.net/pull/5895) [Treat all exceptions thrown inside `EndpointReader` message dispatch as transient, Ported from 1.4](https://github.com/akkadotnet/akka.net/pull/5972) [Fix SSL enable HOCON setting](https://github.com/akkadotnet/akka.net/pull/6038) __Akka.Streams__ [Allow GroupBy sub-flow to re-create closed sub-streams, backported to 1.4](https://github.com/akkadotnet/akka.net/pull/5874) [Fix ActorRef source not completing properly, backported to 1.4](https://github.com/akkadotnet/akka.net/pull/5875) [Rewrite `ActorRefSink` as a `GraphStage`](https://github.com/akkadotnet/akka.net/pull/5920) [Add stream cancellation cause upstream propagation, ported from 1.4](https://github.com/akkadotnet/akka.net/pull/5949) [Fix `VirtualProcessor` subscription bug, ported from 1.4](https://github.com/akkadotnet/akka.net/pull/5950) [Refactor `Sink.Ignore` signature from `Task` to `Task<Done>`](https://github.com/akkadotnet/akka.net/pull/5973) [Add `SourceWithContext.FromTuples()` operator`](https://github.com/akkadotnet/akka.net/pull/5987) [Add `GroupedWeightedWithin` operator](https://github.com/akkadotnet/akka.net/pull/6000) [Add `IAsyncEnumerable` source](https://github.com/akkadotnet/akka.net/pull/6044) __Akka.TestKit__ [Rewrite Akka.TestKit to work asynchronously from the ground up](https://github.com/akkadotnet/akka.net/pull/5953)