root@LOG01:/var/log/graylog/server# ls @400000005c0798832faa27f4.s@400000005c0b41a608f54814.s config @400000005c08ea0330d198c4.s@400000005c0f21e1180b6f04.u current @400000005c09e39a15f325f4.u@400000005c0f2709150f3664.u lock @400000005c09e67b2a37da8c.u@400000005c0f7601302d4274.u state @400000005c09ef4333fd883c.u@400000005c0f8b7b091395e4.u
root@LOG01:/var/log/graylog/server#
Seems that a whole bunch of the services needed are down and not (re)starting.
The message in the browser also clearly suggests that you check the logs in /var/log/graylog/*/current. These should probably give you a hint or two. These logs are also needed if you’d like us to help.