diff --git a/lightsim2grid/lightSimBackend.py b/lightsim2grid/lightSimBackend.py
index 04fb0c7..bbb7599 100644
--- a/lightsim2grid/lightSimBackend.py
+++ b/lightsim2grid/lightSimBackend.py
@@ -1129,7 +1129,9 @@ def runpf(self, is_dc : bool=False) -> Tuple[bool, Union[Exception, None]]:
                     self._debug_Vdc = self._grid.dc_pf(copy.deepcopy(self.V), self.max_it, self.tol)
                     self._grid.reactivate_result_computation()
                     if self._debug_Vdc.shape[0] == 0:
-                        raise BackendError(f"Divergence of DC powerflow (non connected grid) at the initialization of AC powerflow. Detailed error: {self._grid.get_dc_solver().get_error()}")
+                        raise BackendError(f"Divergence of DC powerflow (non connected grid) at the "
+                                           f"initialization of AC powerflow. Detailed error: "
+                                           f"{self._grid.get_dc_solver().get_error()}")
                     V_init = 1. * self._debug_Vdc
                 else:
                     V_init = copy.deepcopy(self.V)
diff --git a/lightsim2grid/tests/test_n1contingencyrewards.py b/lightsim2grid/tests/test_n1contingencyrewards.py
index 346c7f4..477e3fe 100644
--- a/lightsim2grid/tests/test_n1contingencyrewards.py
+++ b/lightsim2grid/tests/test_n1contingencyrewards.py
@@ -122,17 +122,20 @@ def _aux_test_reward(self, obs, reward):
         obs._obs_env.backend._grid = grid_cpy
         obs._obs_env.backend._reset_res_pointers()
         obs._obs_env.backend._grid.tell_solver_need_reset()
+        Vinit = np.ones(grid_cpy.total_bus(), dtype=complex)
+        V = grid_cpy.dc_pf(Vinit, 1, 1e-5)
+        print(f"{V.shape[0] = }, {V[0]:.3f}, {V[1]:.3f}")
         print(f"Obs env {obs._obs_env.backend._grid.get_solver_type()}")
         print(f"Obs env {obs._obs_env.backend._grid.get_dc_solver_type()}")
         sim_obs, sim_r, sim_d, sim_i = obs.simulate(self.env.action_space(), time_step=0)
-        print(f"without contingency: {sim_d = }, {sim_i['exception']}")
+        # print(f"without contingency: {sim_d = }, {sim_i['exception']}")
         print(f"without contingency: {sim_d = }, {sim_i}")
         # print("test:")
         for l_id in self.my_ids:
             sim_obs, sim_r, sim_d, sim_i = obs.simulate(self.env.action_space({"set_line_status": [(l_id, -1)]}),
                                                         time_step=0)
             if not self.is_dc():
-                print(f"for {l_id}: {sim_d = }, {sim_i['exception']}, {(sim_obs.a_or / obs._thermal_limit).max()}")
+                # print(f"for {l_id}: {sim_d = }, {sim_i['exception']}, {(sim_obs.a_or / obs._thermal_limit).max()}")
                 if np.any(sim_obs.a_or > obs._thermal_limit * self.threshold_margin()) or sim_d:
                     unsafe_cont += 1       
             else: