The errors occurs when building the project in Visual Studio.
I am trying to build the sample bilingual filetype for SDL Studio 2019 as described here:
The reference to Sdl.Core.Pluginframework is added to the project. I tried updating the packages via Nuget package manager, tried various .NET frameworks, different Visual Studio Versions, building for x86 and x64 plattforms. I also tried copypasting the sample code into an existing and functioning filetype project where Sdl.Core.Pluginframework is referenced and used (which brought me to the same error). Nothing has helped so far to ged rid of the error.
I would appreciate any guesses how to solve the problem!