I'm having a similar issue (today is my first attempt to do anything like this). I'm seeing this in my logs:
==> service.log.0 <==
[09.14.15 02:50:26.045 INFO Sel-UI-A com.backup42.service.ui.UIController ] UISession Created - 707078160592533329
[09.14.15 02:50:28.968 INFO MQ-UI-1 com.backup42.service.ui.UIController ] UserActionRequest: StatusQueryMessage[707078160592533329] CPD|b1afc65c-574f-4f94-97a1-e07293da1412|richard|/Users/richard|
[09.14.15 02:50:28.969 INFO MQ-UI-1 com.backup42.service.ui.UIInfoUtility ] Loaded port=4243 and token from location=/var/lib/crashplan/.ui_info
[09.14.15 02:50:28.969 INFO MQ-UI-1 com.backup42.service.ui.UIController ] Received status request message with invalid token.
[09.14.15 02:50:28.969 INFO Factory$Notifier-UI0 com.backup42.service.ui.UIController ] UISession Ended after less than a minute - 707078160592533329
[09.14.15 02:50:28.969 INFO Factory$Notifier-UI0 backup42.service.backup.BackupController] UI:: AUTO IDLE... lowBandwidth=25600 B/s, activeThrottleRate=20
[09.14.15 02:50:28.969 INFO Factory$Notifier-UI0 com.backup42.common.command.CliExecutor ] RUN COMMAND: auto.idle > CommandResult@203895406[ auto.idle, success=true, result=null ]
It looks to me like the token is incorrect; looking at the .ui-info file I see "4243,unRAID" is all that is in the file. Perhaps something has changed and this doesn't work anymore?