777 error is usually a connection timeout error. It is an error that can occur when you are using an online application/website that requires a user to Sign In. In these cases, the system is in a session and can timeout and cause the browser to get “confused.”
As a general rule, this error is a non-fatal error and can be caused by many factors outside of TeamUnify’s and the clients control. If the problem persists, please close all browsers and restart.