diff --git a/src/backscattering_experimental_data/factory/measurement.py b/src/backscattering_experimental_data/factory/measurement.py
index 8df919c..54f853f 100644
--- a/src/backscattering_experimental_data/factory/measurement.py
+++ b/src/backscattering_experimental_data/factory/measurement.py
@@ -2,10 +2,12 @@ from astropy.units import (
     Quantity,
     W,  # pyright: ignore[reportAttributeAccessIssue]
     mW,  # pyright: ignore[reportAttributeAccessIssue]
+    s,  # pyright: ignore[reportAttributeAccessIssue]
     Unit,
 )
 from astropy.units.physical import time
-from gwpy.time import Time
+from gwpy.time import Time, from_gps
+from numpy import array, where
 
 from ..component import Component
 from ..lockingstate import LockingState
@@ -99,10 +101,27 @@ class MeasurementFactory:
             frame="trend",
             force_virgotools=force_virgotools,
         )
-        if sum(data["V1:META_ITF_LOCK_index"].diff().abs()) != 0:
-            raise Exception(
-                "The state of the interferometer change in this measurement"
+        state_data = data["V1:META_ITF_LOCK_index"].data.astype(int)
+        if sum(state_data.diff().abs()) != 0:
+            indexes = where(array(state_data.diff().data) != 0)[0]
+            times_change = (
+                data["V1:META_ITF_LOCK_index"].t0
+                + indexes * data["V1:META_ITF_LOCK_index"].dt
             )
+            message = (
+                "state of the interferometer changed in '{}'".format(
+                    name
+                )
+            )
+            for i in range(len(indexes)):
+                time_change = times_change[i]
+                index = int(indexes[i])
+                message += "\nat {}, from {} to {}".format(
+                    from_gps(time_change.to(s).value),
+                    LockingState(state_data[index]).name,
+                    LockingState(state_data[index + 1]).name,
+                )
+            raise Exception(message)
         state = LockingState(data["V1:META_ITF_LOCK_index"].data[0])
         injection_power = data["V1:INJ_IMC_TRA_DC_mean"].mean()
         dark_fringe_power = data["V1:DET_B1p_DC_mean"].mean()