If, like me, you are trying to transfer a domain away from register.com, you’ll probably end up running into this message:
Instead of going the “easy” route of requesting an auth code online, just call the customer support number listed there. Navigate the phone tree with 1, 1, and 2, and let the rep know you want to request an auth code for your domain. I was put on hold, then received an email, and finished the call all within 10 minutes. That beats the heck out of waiting 3-4 days.