System.Exception: Could not connect to UiPath Robot Service. Make sure the service is started! at UiPath.Models.UiPathDuplexProxy.FaultTolerantProxy.CheckAvailability() at UiPath.Models.UiPathDuplexProxy.GetRobotConnectionStatus() at UiPath.Studio.Plugin.Workflow.Services.RobotStudioBridge.Execute(WorkflowDocument document, Boolean isDebugging)
@sumios Follow below post
no, i tried but not working, my version .2018.3.1
@sumios try this
Navigate to ‘C:\Users\username\AppData\Local\UiPath\app-18.*’ and Run UiRobot.exe
Go to start and search UiPath robot. You will find it there. 
it shows as error connecting to robot service
@sumios check below link
Anil_G
ashokkarale
Eric_Alvarado
Yoichi
Julian_Muhlbauer
SorenB
lbowen
ayumi.ouchi
lska
ppr