Switching the payment method from Credit Card to Direct Deposit worked. It autofilled my details from a previous year, leaving me to wonder if the bug was that I had 2 payment methods both filled out even though I didn't have Direct Deposit selected this time.
A TurboTax engineer should really look into this, as based on this forum thread, it is clearly losing you business and shouldn't be a complicated fix. At the very least, you could improve the error message to say something beyond "A server error has occurred". Customers aren't going to get any value from that, and neither are the engineers. It's super generic.
