how to resolve “Unable to find package” nuget error

Question

Working on creating a nuget pkg for a project (A.csproj) which depends on another project (B.csprojec) added as a project reference.
Here is the .nuspec ,

Answer 1

for me: %appdata%\NuGet\NuGet.Config contained only

after doing

nuget sources add -Name "NuGet official package source" -Source "https://api.nuget.org/v3/index.json"

this was added

afterwards packeges were found.