Error NU1605 Detected package downgrade

Question

I am experiencing the following NU1605 dependency errors in my netcoreapp2.0 console application:

NU1605  Detected package downgrade: System.Dia         


        

Answer 1

Something that I've run into that causes this error is having multiple references to the same package in one or more .csproj files. In our case, these references are to local dependencies in our own nuget repository.

This is invisible to a developer in Visual Studio, so you need to open the .csproj file in a separate editor.

For my team, I think the cause is a combo of a lot of churn in both a dependent library and the solution that consumes that dependency. For whatever reason, a git merge will take both versions in the .csproj file without raising a conflict. In several project files, I found 3 versions of the same dependency.