Unable to load the service index for source https://api.nuget.org/v3/index.json in VS2017?

Question

I am getting This error:

[nuget.org] Unable to load the service index for source https://api.nuget.org/v3/index.json. An error occurred while send

Answer 1

I got this error using VSTS as source provider (git). Was logged in to a MSDN account in VS2017 based on the correct email address, i.e. same as the one used for my VSTS login. Upon restoring packages from the VSTS nuget-feed, I would repeatedly be prompted to log in to my MSDN-account, but still get 401 from the source/feed.

Turned out, I apparently had 2 different MSDN-accounts on the same email address - 1 "Personal" account and 1 "Work or school" account.

Solution: simply log in with the correct one (which here turned out to be the Work one)