Why would employees receive error message: "No workflow found." when applying for leave or claims?

Why would employees receive error message: "No workflow found." when applying for leave or claims?

Insert the appliable recipient's email addresses, in the "Notify email recipients on advanced leave approvals" field, under the Employee self service section on the Leave Settings screen, to notify an additional person/people when leave applications are approved.

      Navigate > Configuration > Human Resources > Leave Administration > Leave Settings > Employee self service