Cannot Start Attended Jobs From UiPath Apps or UiPath Studio Web Apps in UiPath Assistant Due To Error 500 - Robot Service Down

[system]

How to resolve the '500 - Robot Service Down' error while trying to run attended jobs from UiPath Apps or UiPath Studio Web Apps in UiPath Assistant?

Issue Description

Scenario #1

Users attempting to open a UiPath Studio Web App through UiPath Assistant encounter a failure with the following error messages:

Attended process exception. Please reload page or contact your administrator.
Job has failed.
The UiPath Assistant is required to complete this action.
Don't have the UiPath Assistant? Get it now.

UiPath Assistant Console Logs (when UiPath Assistant is running in Debug mode with command UiPath.Assistant.exe --dbg cli flag and then press Ctrl+Shift+I):

Scenario #2

Users attempting to open a UiPath Apps Classic App (UiPath Apps Studio) through UiPath Assistant encounter a failure with the following error:

Process Error
500 - Robot Service down
The UiPath Assistant is required to complete this action.
Don't have the UiPath Assistant? Get it now.

UiPath Assistant Console Logs (when UiPath Assistant is running in Debug mode with command UiPath.Assistant.exe --dbg cli flag and then press Ctrl+Shift+I):

Failed to load resource: net::ERR_CONNECTION_REFUSED localhost:2323/GetPort:1

Root Cause

• The UiPath JavaScript Robot Add-on (JavaScriptAddOn parameter when it is installed/updated from a command line) was not installed with the Robot installation

• The UiPath RobotJS does not exists in the Task Scheduler.

• The UiPath RobotJS exists in Task Scheduler, but it is not running

• In services.msc, the UiPath RobotJS Service is missing or it is not running.

Resolution

Modify or upgrade the Robot installation and include the UiPath JavaScript Robot Add-on feature in the Control Panel -> Programs -> Programs and Features -> UiPath Studio or UiPath Robot or UiPath Platform -> Change

More details:

Robot developer guide

Robot clean installations - command line parameters