Hello, I have the same issue when I try to set my first e-mail account on a fresh installation of GO on Debian Ubuntu. I can't set because of the error but no field is highlighted for check. When I press OK or apply button pop-up message appears and I cannot complete the operation. Is possible I've made a mistake but I cannot see it (it is a simple external account with IMAP and SMTP).
Thanks you in advance for support.