I had error when run Monitor Program

[ISand6]

When I run monitor program, I had this error:

insandjaja@pop-os:~/intelFPGA_lite/18.1/University_Program/Monitor_Program/bin$ ./intel-fpga-monitor-program

Java HotSpot(TM) 64-Bit Server VM warning: You have loaded library /home/insandjaja/flexdock/RubberBand.so which might have disabled stack guard. The VM will try to fix the stack guard now.

It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.

java.net.ConnectException: Connection refused

   at java.net.PlainSocketImpl.socketConnect(Native Method)

   at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)

   at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)

   at java.net.AbstractPlainSocketImpl.connect(Unknown Source)

   at java.net.SocksSocketImpl.connect(Unknown Source)

   at java.net.Socket.connect(Unknown Source)

   at java.net.Socket.connect(Unknown Source)

   at java.net.Socket.<init>(Unknown Source)

   at java.net.Socket.<init>(Unknown Source)

   at org.flexdock.docking.drag.outline.x11.Connection.<init>(Connection.java:35)

   at org.flexdock.docking.drag.outline.x11.Graphics.create(Graphics.java:49)

   at org.flexdock.docking.drag.outline.x11.Graphics.<clinit>(Graphics.java:34)

   at org.flexdock.docking.drag.outline.x11.X11RubberBand.<clinit>(X11RubberBand.java:14)

   at java.lang.Class.forName0(Native Method)

   at java.lang.Class.forName(Unknown Source)

   at org.flexdock.util.Utilities.createInstance(Utilities.java:285)

   at org.flexdock.docking.drag.effects.EffectsManager.createRubberBand(EffectsManager.java:94)

   at org.flexdock.docking.drag.effects.EffectsManager.loadSystemRubberband(EffectsManager.java:137)

   at org.flexdock.docking.drag.effects.EffectsManager.prime(EffectsManager.java:43)

   at org.flexdock.docking.drag.effects.EffectsManager.<clinit>(EffectsManager.java:37)

   at org.flexdock.docking.drag.DragManager.prime(DragManager.java:42)

   at org.flexdock.docking.DockingManager.init(DockingManager.java:137)

   at org.flexdock.docking.DockingManager.<clinit>(DockingManager.java:127)

   at monitor.ui.UIManager.initDocking(UIManager.java:337)

   at monitor.ui.UIManager.init(UIManager.java:160)

   at monitor.globals.Globals.init(Globals.java:87)

   at monitor.Main.main(Main.java:36)

How to fix this?