Project cannot be published. Main file has validation errors

Hi! First of all, thank you for your help. I’m working with UiPath studio and my problem is that when I try to publish my project the system show me this message:

Project cannot be published. Main file has validation errors.

But when I execute in design or execute mode works fine without any error.

This are the logs
System.Exception: Project cannot be published. Main file has validation errors. —> System.Activities.InvalidWorkflowException: Main
at UiPath.Workflow.ViewModels.MainViewModel.CheckProjectForErrors()
at UiPath.Workflow.ViewModels.MainViewModel.PackAndPush()
— End of inner exception stack trace —

What I’m doing wrong?