Visual Studio 2010 nuget error: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel

Question

Whenever I\'m trying to install something or even just list the packages I get this error \"The underlying connection was closed: Could not establish trust relationship for

Answer 1

Related: ServicePointManager does not support proxies with the https scheme

If you've previously had Fiddler open, you might well have a certificate for nuget.org that is invalid.

If so, open up MMC, add the Certificates snapin (current User) and remove nuget.org from the Personal store.

Due to Nuget keeping a handle to this cert (seemingly) you will have to restart Visual Studio. Afterwards, you should have a good time.