ConfigurationManager in a .NET Core application

Question

I get the following error upon application debug/launch:

System.TypeInitializationException: 'The type initializer for 'System.Data.Entity.Internal.AppConfig' threw an exception.'

FileNotFoundException: Could not load file or assembly 'System.Configuration.ConfigurationManager, Version=4.0.2.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.

With the following piece of code that uses DatabaeContext:

private CamelotViewsStandardContext db = new CamelotViewsStandardContext();

The project is on the .NET Core 3.0 with System.Configuration.ConfigurationManager NuGet package installed. It works on the previous version which is on the .NET Core 2.2 so no idea why it is not working on 3.0?

The code behind the reference for creating the database context is using Entity Framework, which is supposed to be supported in 3.0?

Answer 1

This happened to me when I upgraded a project from .NET Core 2.2 to 3.1. Unit tests would pass but the exception would be thrown when the webapp was deployed. I resolved it by adding

<PackageReference Include="System.Configuration.ConfigurationManager" Version="4.7.0" />
<PackageReference Include="System.Management" Version="4.7.0" />

to the .csproj file for the project.

Reference: https://github.com/dotnet/runtime/issues/627