The quick fix if you do not mind using a new nuget source locally will be to run the following command:
dotnet new nugetconfig
After that you should get the following output:
Getting ready... The template "NuGet Config" was created successfully.
Where are my nuget source folders?
The source folders serve as cache. In order to list the folder you can use the following command:
dotnet nuget locals all -l
If you run only “dotnet nuget locals” you will find more information that can be listed.
Hope that this has unblocked you 🙂