private void LoadRoles() { AuthenticationServiceClient client = new AuthenticationServiceClient(); Task <Role[]> rolesTask = client.GetAllRolesAsync(); rolesTask.ContinueWith(task => { Invoke(new Action(() => { try { comboBoxRole.Items.Clear(); foreach (string role in task.Result.Select(r => r.RoleName)) { comboBoxRole.Items.Add(role); } Enabled = true; } catch (FaultException <Models.Faults.InvalidRoleFault> exc) { MessageBox.Show(exc.Message); } catch (FaultException exc) { MessageBox.Show(exc.Message); } })); }); }