ERROR: Visual Studio 2010 nuget error: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
Go to VS2010 -> Tools -> Library Package Manager -> Package Manager Settings
Choose Package Manager -> Package Sources.
1. Add a new package source as:
2. Move Up the newly added package source to first position.
3. UnCheck existing "Nuget official package source"
4. Restart VS2010.