Adding reference to "Microsoft.Extensions.Hosting" Version="5.0.0" kills the service

If a project references both CoreWCF and "Microsoft.Extensions.Hosting" Version="5.0.0" (which is a substantial part of NET5), then WCF service fails to start with the error like this one:

fail: Microsoft.AspNetCore.Server.Kestrel[0]
      Heartbeat.OnHeartbeat
      System.TypeLoadException: Could not load type 'Microsoft.Extensions.Primitives.InplaceStringBuilder' from assembly 'Microsoft.Extensions.Primitives, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
         at Microsoft.Net.Http.Headers.DateTimeFormatter.ToRfc1123String(DateTimeOffset dateTime, Boolean quoted)
         at Microsoft.Net.Http.Headers.HeaderUtilities.FormatDate(DateTimeOffset dateTime, Boolean quoted)
         at Microsoft.Net.Http.Headers.HeaderUtilities.FormatDate(DateTimeOffset dateTime)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.DateHeaderValueManager.SetDateValues(DateTimeOffset value)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.DateHeaderValueManager.OnHeartbeat(DateTimeOffset now)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.Heartbeat.OnHeartbeat()

This is sort of a known issue because CoreWCF references an obsolete package "Microsoft.AspNetCore" Version="2.2.0", which, in turn, results in this error when "Microsoft.Extensions.Hosting" Version="5.0.0" is also used: https://github.com/dotnet/aspnetcore/issues/27986

Known workarounds:
As advised in the reference above, add

  <ItemGroup>
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>

into any project that references "Microsoft.Extensions.Hosting" Version="5.0.0". It appears that even a single reference in some lower level project is enough. So, perhaps adding this reference into CoreWCF itself will do the trick.

Repro steps:

1. Build CoreWCFWithSamples.sln.
2. Navigate to e.g. C:\GitHub\CoreWCF\bin\Debug\NetCoreServer\netcoreapp3.1 (adjusted to point to a proper local folder), then run NetCoreServer.exe.
3. Observe that it runs without errors.
4. Add a reference to "Microsoft.Extensions.Hosting" Version="5.0.0" to the project NetCoreServer.
5. Clean / rebuild the solution, then try running NetCoreServer.exe.
6. Observer that now it starts producing the exception above.

This is fairly severe as reference to "Microsoft.Extensions.Hosting" Version="5.0.0" is pretty much a must in almost any NET5 web related app. Attached is the full log of running NetCoreServer.exe with Microsoft.Extensions.Hosting added.

I would suggest re-targeting CoreWCF to NET5 instead of NetCore 3.1, then fix what’s broken.

ErrLog.txt

[mconnew]

Work to support the latest version of .NET Core will happen after the initial GA release happening later this month.

[mconnew]

If you specify using the 2.1 version as a direct dependency in your app it will override whatever any over dependency is trying to pull it. As long as they aren’t using api’s which only exist in the newest version of the package, that has a good chance of working.