When executing ./agent.sh console with the user owner of the qb installation dir i get:

Running QuickBuild Build Agent...
wrapper | --> Wrapper Started as Console
wrapper | Java Service Wrapper Standard Edition 64-bit 3.5.30
wrapper | Copyright (C) 1999-2016 Tanuki Software, Ltd. All Rights Reserved.
wrapper | http://wrapper.tanukisoftware.com
wrapper | Licensed to PMEase Inc. for QuickBuild
wrapper |
wrapper | Launching a JVM...
jvm 1 | WrapperManager: Initializing...
jvm 1 | 2018-03-22 15:42:44,761 INFO - Cleaning cached plugin libraries...
jvm 1 | 2018-03-22 15:42:44,823 INFO - Cleaning temp directory...
jvm 1 | 2018-03-22 15:42:44,827 INFO - Benchmarking...
jvm 1 | 2018-03-22 15:42:46,404 INFO - Connecting to server 'http://quickbuildserver:8810'...
jvm 1 | 2018-03-22 15:42:46,456 INFO - Updating framework...
jvm 1 | 2018-03-22 15:42:46,462 INFO - Updating plugins...
jvm 1 | 2018-03-22 15:42:46,467 INFO - Updating plugins/com.pmease.quickbuild.libs...
jvm 1 | 2018-03-22 15:42:46,470 INFO - Updating plugins/site...
jvm 1 | 2018-03-22 15:42:46,472 INFO - Updating asset...
jvm 1 | 2018-03-22 15:42:46,474 INFO - Booting QuickBuild from '/opt/quickbuild/buildagent'...
jvm 1 | 2018-03-22 15:42:46,475 INFO - Starting framework...
jvm 1 | 2018-03-22 15:42:46,509 INFO - Caching plugin libraries...
jvm 1 | WrapperStartStopApp:
jvm 1 | WrapperStartStopApp Error: Encountered an error running start main: java.lang.reflect.InvocationTargetException
jvm 1 | WrapperStartStopApp Error: java.lang.reflect.InvocationTargetException
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
jvm 1 | WrapperStartStopApp Error: at java.lang.reflect.Method.invoke(Method.java:497)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.bootstrap.Bootstrap.boot(Bootstrap.java:576)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.bootstrap.Bootstrap.main(Bootstrap.java:126)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
jvm 1 | WrapperStartStopApp Error: at java.lang.reflect.Method.invoke(Method.java:497)
jvm 1 | WrapperStartStopApp Error: at org.tanukisoftware.wrapper.WrapperStartStopApp.run(WrapperStartStopApp.java:400)
jvm 1 | WrapperStartStopApp Error: at java.lang.Thread.run(Thread.java:745)
jvm 1 | WrapperStartStopApp Error: Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.bootstrap.BootstrapUtils.wrapAsUnchecked(BootstrapUtils.java:56)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.equinoxadapter.EquinoxAdapter.startup(EquinoxAdapter.java:61)
jvm 1 | WrapperStartStopApp Error: ... 12 more
jvm 1 | WrapperStartStopApp Error: Caused by: java.lang.reflect.InvocationTargetException
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
jvm 1 | WrapperStartStopApp Error: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
jvm 1 | WrapperStartStopApp Error: at java.lang.reflect.Method.invoke(Method.java:497)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.equinoxadapter.EquinoxAdapter.startup(EquinoxAdapter.java:59)
jvm 1 | WrapperStartStopApp Error: ... 12 more
jvm 1 | WrapperStartStopApp Error: Caused by: java.lang.NoClassDefFoundError: javax/servlet/http/HttpSessionIdListener
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.server.session.SessionHandler.<clinit>(SessionHandler.java:54)
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.servlet.ServletContextHandler.newSessionHandler(ServletContextHandler.java:241)
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.servlet.ServletContextHandler.getSessionHandler(ServletContextHandler.java:334)
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.servlet.ServletContextHandler.relinkHandlers(ServletContextHandler.java:180)
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.servlet.ServletContextHandler.<init>(ServletContextHandler.java:157)
jvm 1 | WrapperStartStopApp Error: at org.eclipse.jetty.servlet.ServletContextHandler.<init>(ServletContextHandler.java:117)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.Quickbuild.startJettyServer(Quickbuild.java:339)
jvm 1 | WrapperStartStopApp Error: at com.pmease.quickbuild.Quickbuild.start(Quickbuild.java:252)
jvm 1 | WrapperStartStopApp Error: ... 17 more
jvm 1 | WrapperStartStopApp Error: Caused by: java.lang.ClassNotFoundException: javax.servlet.http.HttpSessionIdListener
jvm 1 | WrapperStartStopApp Error: at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
jvm 1 | WrapperStartStopApp Error: at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
jvm 1 | WrapperStartStopApp Error: at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
jvm 1 | WrapperStartStopApp Error: ... 25 more
jvm 1 | 2018-03-22 15:42:49,370 INFO - Stopping QuickBuild agent...
jvm 1 | 2018-03-22 15:42:49,669 INFO - Disconnecting from server...
jvm 1 | 2018-03-22 15:42:49,674 INFO - Waiting for finish of existing jobs...
jvm 1 | 2018-03-22 15:42:49,675 INFO - Stopping plugins...
jvm 1 | 2018-03-22 15:42:49,678 INFO - Stopping task scheduler...
jvm 1 | 2018-03-22 15:42:49,719 INFO - QuickBuild agent stopped.
wrapper | <-- Wrapper Stopped

The first time i ran it, it worked i authorized the node in the server but suddenly disappeared and started failing after executing the above.

java version "1.8.0_66"