Hmm, this one is a bit tricky --- if clearing your cache didn't help, you might be the victim of overzealous network hardware. Please see this post for some more details:
I'm sorry I don't have a better answer for you - this gets into the realm of conda, which is something we don't develop. If your workstation is mobile (e.g. a laptop), maybe try from a new network? Sorry, and good luck - keep us posted!
