reference .Net framework 4.5.2 from .Net Core 2.0 project

I have spent a few hours trying to figure out why .Net Core 2.0 wouldn't load .Net framework 4.5.2 nuget packages.

Now I think it's time to ask...

What happens is I have a .Net Core 2.0 WebApi app (A) and I want to reuse my .Net framework 4.5.2 library(B).

I created nuget packages for B and referenced the nuget package in the A.

The libraries are downloaded in the C:\Users\username.nuget\packages folder But when I consume B in the code, it errors me out saying

System.IO.FileLoadException: 'Could not load file or assembly 'xxx.TradeServices.Common, Version=2.1.289.1, Culture=neutral, PublicKeyToken=null'. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'

I then added some dummy code

var client = new TradeServicesClient(EnvironmentType.Production);

xxx.TradeServices.Common is loaded.

But another exception appear saying cannot load dependency dll.

FileNotFoundException: Could not load file or assembly 'Ice, Version=3.7.0.0, Culture=neutral, PublicKeyToken=0c5ebb72d74932c6'. The system cannot find the file specified.

I have checked all the dependencies, they are downloaded correctly in the

C:\Users\username.nuget\packages

folder

I am not sure about why .Net Core is behaving this way. It seems the dependency chain is not loaded. Could you please help me to figure out what's going on?

asp.net core can target multiple frameworks; a 2.0 web app will typically run on either "netcoreapp2.0" (a .NET Core application) or "net461" (a .NET application), for example - as specified by the <TargetFramework> in the csproj. It is this <TargetFramework> that determines how all the downstream package resolution will work. If it is "net461", it may be happy to take a "net452" library. However, "netcoreapp2.0" will not want "net452" - instead preferring "netstandard2.0" or "netstandard1.6", etc. Targeting .NET Standard will mean that all downstream packages also need to target .NET Standard, which is not always possible.

So:

• if possible, make your dependencies target some version of .NET Standard
• if that isn't possible, ensure that the <TargetFramework> is "net461" or similar

Edit: it looks like the default projects also change between Microsoft.AspNetCore (when targeting .NET) and Microsoft.AspNetCore.All (when targeting .NET Core) - so you may also need to change that <PackageReference ... /> entry in the csproj. If you are using any of the extra packages in Microsoft.AspNetCore.All that aren't in Microsoft.AspNetCore - you may need to add the ones that you need manually.