Bug: UiElements cannot be passed as out-arguments in isolated, parallel worklows

Hi Together

While experimenting with parallel activities I’ve found a further bug.
Invoke a worklow isolated, in a parallel activity. Create a simple UiElement and pass it as an out-argument. You will get an error. I did not try any other Ui-variable types. Studio version doesn’t matter.

Please use the xaml to reproduce. Bug reports.zip (3,4 KB)

  "name": "BlankProcess",
  "description": "Blank Process",
  "main": "Main.xaml",
  "dependencies": {
	"Microsoft.Activities.Extensions": "[]",
	"UiPath.System.Activities": "[20.4.0]",
	"UiPath.UIAutomation.Activities": "[20.4.1]"
  "webServices": [],
  "schemaVersion": "4.0",
  "studioVersion": "",
  "projectVersion": "1.0.0",
  "runtimeOptions": {
	"autoDispose": false,
	"isPausable": true,
	"requiresUserInteraction": true,
	"supportsPersistence": false,
	"excludedLoggedData": [
	"executionType": "Workflow"
  "designOptions": {
	"projectProfile": "Developement",
	"outputType": "Process",
	"libraryOptions": {
	  "includeOriginalXaml": false,
	  "privateWorkflows": []
	"fileInfoCollection": []
  "expressionLanguage": "VisualBasic"

Thanks for your report, we will investigate.

Hi @Enrico

See here: