Sitefinity 15.4 | Upgrade - Fix NuGet package error "Unable to find package"

Описание: This video explains a Sitefinity 15.4 upgrade issue caused by migrating NuGet packages from Progress’s private feed (nuget.sitefinity.com) to nuget.org, and shows how to fix it by updating your package source mapping.

"Unable to find metadata for Progress.Sitefinity.xxx 15.4.860.490"

"Unable to find package Progress.Sitefinity.xxx with version (=15.4.860.490)
Found 1 version(s) in nuget.sitefinity.come [Newest version: 15.4.8600.319-alpha]"