If you have purchased a program and receive an error when attempting to join a course session: "There was an error. Please reload the page and try again" this is usually because you have not yet completed account confirmation.
Check your email account for a message titled "Action Required: Confirm your email" and click the link to confirm.
If you cannot find this email, reset your password from your Account Settings or the Log In page. Clicking the reset link in your email will also confirm your account.