I downloaded the ServiceStack BSD version 3.9.71 from Nuget
using the commmands
Install-Package ServiceStack -Version 3.9.71
and Install-Package ServiceStack.Plugins.ProtoBuf -Version 3.9.71
I installed also the protobuf-net
Install-Package protobuf-net
but I have problem because the ServiceStack 3.9.71 try to find the protobuf-net ver.2.0.0.640,
when the last version of protobuf from Nuget is 2.0.0.668
The NuGet packages doesn't specify a version constraint on them so they get the latest dependency, in this case v2.0.0.668. You could uninstall the current version of protobuf-net and just install the one that's needed, e.g:
Otherwise another option is to add Binding Redirects in your web.config.
I'll look at specifying explicit versions for external NuGet dependencies in future.