Can't use System.Configuration.Configuration manager in a .NET Standard2.0 library on .NET FX4.6

Solution 1:

As @kiran mentioned in a comment you can solve this by running:

Install-Package System.Configuration.ConfigurationManager

in NuGet Package Manager

Solution 2:

It is not possible to create .NET Standard library which references System.Configuration.ConfigurationManager package and uses ConfigurationManager class. Once library adds reference to .NET Core specific package it ceases to be portable .NET Standard library since it is bound to framework specific package.

.NET Standard 2.0 does not contain System.Configuration.ConfigurationManager API. Therefore, the only way to use this API is to build one version of the library against .NET Core System.Configuration.ConfigurationManager package which can be used on .NET Core and have a second version of the library which is build against .NET FX System.Configuration assembly and can be used on .NET FX.

Solution 3:

Had the same issue and after installing the same System.Configuration.ConfigurationManager package in the FX4.6 project resolved this issue.