Accept updated License agreement
Apple updates their Apple Developer program license agreement periodically. You will receive emails from Apple to remind you to agree with the new agreement. If you don't do that, your Apple Publish can fail.
During the publishing AppMachine will let you know that your agreement needs to be reviewed.
In AppMachine, the error you receive will look like this:
Go to the your Apple Developer Account and review the agreement.
Confirm that you've read the updated agreement by checking the checkbox and click on "I Agree."