"Connection insecure" error when trying to manage a Gmail or Yahoo account About a week ago, I was prompted to reset my Yahoo e-mail password. So I went to System Preferences -> Internet Accounts and double clicked on Ymail (the Yahoo e-mail account). I saw this screen:



Followed shortly by this error message:



Dismissing the error message does nothing to the first window, and eventually I have to cancel.

Strangely, I noticed this same behavior has happened when I double-click on my Gmail account, despite the fact that the password still seems to be valid.

I have seen this behavior both at my home and my local coffee shop. To my knowledge, I am not using a proxy. What can I do to solve this "Connection Insecure" problem when trying to manage a Gmail or Yahoo account?
Check the Login/Certificates container in the keychain for anything with a red mark that says "Certificate is invalid". It's probably an old CA on the box that's conflicting with the current one from those accounts.