Posted 22 April 2020, 2:27 am ESTGrapeCity is no longer publishing the latest version of its ComponentOne NuGet packages to the private repository, nuget.grapecity.com. All packages have been simultaneously uploaded to the NuGet Gallery (nuget.org), and moving forward we will only be publishing to the NuGet Gallery.
If have installed an older version of the C1ControlPanel from 2019 or earlier, you may need to manually remove the GrapeCity package source from Visual Studio.
To manually remove the nuget.grapecity.com source:
1. In Visual Studio, go to Tools - NuGet Package Manager - Package Manager Settings
2. Under the NuGet Package Manager node, select Package Sources
3. Select the GrapeCity (nuget.grapecity.com) source and click the "X" delete button.
Make sure you have nuget.org checked, and Visual Studio will then be able to find the GrapeCity packages for your project.