There are two new configuration options available which can be added to the file /opt/open-xchange/etc/as-config.yml

# If set the UI will redirect to this URL in case any error occurred.
# The redirect will also included additional parameter (language, statusCode, statusText, error)
# which will be added to the hash value of the URL. Those parameter could be used to display an error.
samlLoginErrorRedirectURL: {string}

# If set to true and saml-login has been enabled the login form won't be shown at all.
# It will rather display the server down page. This parameter won't work if the
# redirect option has been enabled (see above)
samlLoginErrorPage: true || false (default)