NuGet fails: "The underlying connection was closed: An unexpected error occurred on a send"

Question

I want to install Microsoft ASP.NET Identity Core through the use of Manage Nuget Packages, but when I click the install button the following error occurs:

The underlying connection was closed: An unexpected error occurred on a send

Answer 1

Try pasting the following into a .reg file and run it. Then try running your NuGet command (no reboot required).

Windows Registry Editor Version 5.00  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319] "SchUseStrongCrypto"=dword:00000001  [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319] "SchUseStrongCrypto"=dword:00000001 

Ran into this issue because TLS1.2 was not enabled (similar to Tony's response). Using http does not fix the situation because NuGet redirects to https now that TLS1.2 is enforced.

Answer 2

This is SSL cert issue on http://go.microsoft.com. Change the package source url to http://packages.nuget.org/v1/FeedService.svc/ which works for me.

Source: https://github.com/nuget/home