The large red box error message comes up when the autosave function is not functioning. There are several reasons this may be happening:

Your internet connection is slow. Try and get a stronger signal or connect to a more reliable network.
A firewall is interfering with Sutori's uploader. If you are at school, here are a list of domains to whitelist that you can forward onto the tech department.

If the problem persists, please contact us on the chat or via email and we'll find a solution.