Our project cannot use MessagePack as serializer in SignalR because there is an error on ios. Fortunately, this bug has been fixed #1461, but unfortunately there is no new release with this fix. If I use MessagePack as a serializer I would be able to build the project myself, but it's dependent on Microsoft.AspNetCore.SignalR.Protocols.MessagePack and I won't be able to use SignalR on ios until nuget is updated.