Upgrade from 188.8.131.52 to 184.108.40.206.
Was unable to use Update from Server admin, as following error given:
key [passwordserver] doesn't exist
Replaced jar file in Tomcat folder, restarted Tomcat.
Server Overview page has this error message at top:
Failed to retrieve update information: key [passwordserver] doesn't exist (existing keys:sessionid,urltoken,alwaysNew