Azure search - Inheritance security rules violated by type: 'System.Net.Http.WebRequestHandler'

When I try to use Azure Search on .NET Framework > 4.5.2, it blows up, throwing the above exception:

public SearchServiceClient Create()
{
    return new SearchServiceClient(options.Value.ServiceName, new SearchCredentials(options.Value.SecurityKey));
}

System.TypeLoadException occurred
  HResult=0x80131522
  Message=Inheritance security rules violated by type: 'System.Net.Http.WebRequestHandler'. Derived types must either match the security accessibility of the base type or be less accessible.
  Source=<Cannot evaluate the exception source>
  StackTrace:
   at Microsoft.Rest.ServiceClient`1.CreateRootHandler()
   at Microsoft.Azure.Search.SearchServiceClient..ctor(String searchServiceName, SearchCredentials credentials)
   at Search.Index.Search.SearchClientFactory.Create() in C:\code\Search\solutions\service\Search.Index\Search\SearchClientFactory.cs:line 18

This code is in a class library compiled with .NET Framework 4.5.2. When the executable which includes the class library is also 4.5.2, the above code works. But if I upgrade the executable to 4.6 (or 4.6.1, 4.6.2, 4.7.1) then the code starts throwing the exception.

[mattfrear]

I’ve spent the last couple of hours on this before raising the issue here - and I just figured out a workaround. I’ve added the NuGet package for System.Net.Http 4.3.3 to my class library which contains the above code - and now it works.

[brjohnstmsft]

@mattfrear Thanks for confirming; I just found that issue yesterday. I’m hoping that fixing this will be a simple matter of ensuring that Microsoft.Azure.Search refers to the correct version of whatever dependency refers to System.Net.Http. First I have to repro the issue though. I’m working on that today.