When attempting to rename an Automation Server, the following error is shown:
Validation failed for property 'PrimaryPassword'. Path: '[server path]'. Type 'Password'
Cannot set property value to null because the property is not nullable.
The Automation Server has been cloned using a backup of another Automation Server, and in that process the SMTP server passwords have been set to null.
Configure a password for the primary and secondary SMTP server. It does not matter what the password is set to.