diff --git a/etna/models/nn/timesfm.py b/etna/models/nn/timesfm.py
index a869ec491..0fc504360 100644
--- a/etna/models/nn/timesfm.py
+++ b/etna/models/nn/timesfm.py
@@ -1,4 +1,5 @@
 import os
+import reprlib
 import warnings
 from pathlib import Path
 from typing import Dict
@@ -32,7 +33,8 @@ class TimesFMModel(NonPredictionIntervalContextRequiredAbstractModel):
 
     This model doesn't support forecasting on misaligned data with `freq=None` without exogenous features.
 
-    Use :py:class:`~etna.transforms.TimeSeriesImputerTransform` to fill NaNs for stable behaviour.
+    This model doesn't support NaN in the middle or at the end of time series.
+    Use :py:class:`~etna.transforms.TimeSeriesImputerTransform` to fill them.
 
     Official implementation: https://github.com/google-research/timesfm
 
@@ -179,7 +181,7 @@ def predict(
         """
         raise NotImplementedError("Method predict isn't currently implemented!")
 
-    def _get_exog_features(self) -> List[str]:
+    def _exog_сolumns(self) -> List[str]:
         static_reals = [] if self.static_reals is None else self.static_reals
         static_categoricals = [] if self.static_categoricals is None else self.static_categoricals
         time_varying_reals = [] if self.time_varying_reals is None else self.time_varying_reals
@@ -235,13 +237,20 @@ def forecast(
 
         end_idx = len(ts.index)
 
-        all_exog = self._get_exog_features()
+        all_exog = self._exog_сolumns()
         df_slice = ts.df.loc[:, pd.IndexSlice[:, all_exog + ["target"]]]
-        first_valid_index = df_slice.isna().any(axis=1).idxmin()
+        first_valid_index = (
+            df_slice.isna().any(axis=1).idxmin()
+        )  # If all timestamps contains NaNs, idxmin() returns the first timestamp
 
         target_df = df_slice.loc[first_valid_index : ts.index[-prediction_size - 1], pd.IndexSlice[:, "target"]]
-        if target_df.isna().any().any():
-            raise ValueError("There are NaNs in the middle or end of the time series.")
+
+        nan_segment_mask = target_df.isna().any()
+        if nan_segment_mask.any():
+            nan_segments = nan_segment_mask.loc[:, nan_segment_mask].index.get_level_values(0).tolist()
+            raise ValueError(
+                f"There are NaNs in the middle or at the end of target. Segments with NaNs: {reprlib.repr(nan_segments)}."
+            )
 
         future_ts = ts.tsdataset_idx_slice(start_idx=end_idx - prediction_size, end_idx=end_idx)
 
@@ -249,8 +258,13 @@ def forecast(
             target = target_df.values.swapaxes(1, 0).tolist()
 
             exog_df = df_slice.loc[first_valid_index:, pd.IndexSlice[:, all_exog]]
-            if exog_df.isna().any().any():
-                raise ValueError("There are NaNs in the middle or end of the exogenous features.")
+
+            nan_segment_mask = exog_df.isna().any()
+            if nan_segment_mask.any():
+                nan_segments = nan_segment_mask.loc[:, nan_segment_mask].index.get_level_values(0).tolist()
+                raise ValueError(
+                    f"There are NaNs in the middle or at the end of exogenous features. Segments with NaNs: {reprlib.repr(nan_segments)}."
+                )
 
             static_reals_dict = (
                 {
diff --git a/tests/test_models/test_nn/test_timesfm.py b/tests/test_models/test_nn/test_timesfm.py
index 27f0629ef..3778c432b 100644
--- a/tests/test_models/test_nn/test_timesfm.py
+++ b/tests/test_models/test_nn/test_timesfm.py
@@ -23,6 +23,13 @@ def generate_increasing_df():
     return df
 
 
+def generate_exog():
+    n = 128
+    df_exog = generate_ar_df(start_time="2001-01-01", periods=n + 2, n_segments=2)
+    df_exog.rename(columns={"target": "exog"}, inplace=True)
+    return df_exog
+
+
 @pytest.fixture
 def ts_increasing_integers():
     df = generate_increasing_df()
@@ -54,6 +61,24 @@ def expected_ts_increasing_integers():
     return ts
 
 
+@pytest.fixture
+def ts_exog_middle_nan():
+    df = generate_increasing_df()
+    df_exog = generate_exog()
+    df_exog.loc[120, "exog"] = np.NaN
+    ts = TSDataset(df, df_exog=df_exog, freq="D", known_future="all")
+    return ts
+
+
+@pytest.fixture
+def ts_exog_all_nan():
+    df = generate_increasing_df()
+    df_exog = generate_exog()
+    df_exog["exog"] = np.NaN
+    ts = TSDataset(df, df_exog=df_exog, freq="D", known_future="all")
+    return ts
+
+
 @pytest.mark.smoke
 def test_url(tmp_path):
     model_name = "timesfm-1.0-200m-pytorch.ckpt"
@@ -118,7 +143,7 @@ def test_forecast_failed_nan_middle_target(ts_nan_middle):
     model = TimesFMModel(path_or_url="google/timesfm-1.0-200m-pytorch", encoder_length=128)
     pipeline = Pipeline(model=model, horizon=2)
     pipeline.fit(ts_nan_middle)
-    with pytest.raises(ValueError, match="There are NaNs in the middle or end of the time series."):
+    with pytest.raises(ValueError, match=r"There are NaNs in the middle or at the end of target. Segments with NaNs:"):
         _ = pipeline.forecast()
 
 
@@ -162,7 +187,25 @@ def test_forecast_exog_features_failed_nan_middle_target(ts_nan_middle):
     )
     pipeline = Pipeline(model=model, transforms=transforms, horizon=horizon)
     pipeline.fit(ts_nan_middle)
-    with pytest.raises(ValueError, match="There are NaNs in the middle or end of the time series."):
+    with pytest.raises(ValueError, match="There are NaNs in the middle or at the end of target. Segments with NaNs:"):
+        _ = pipeline.forecast()
+
+
+@pytest.mark.parametrize("ts", ["ts_exog_middle_nan", "ts_exog_all_nan"])
+def test_forecast_exog_features_failed_exog_nan(ts, request):
+    ts = request.getfixturevalue(ts)
+
+    horizon = 2
+    model = TimesFMModel(
+        path_or_url="google/timesfm-1.0-200m-pytorch",
+        encoder_length=128,
+        time_varying_reals=["exog"],
+    )
+    pipeline = Pipeline(model=model, transforms=[], horizon=horizon)
+    pipeline.fit(ts)
+    with pytest.raises(
+        ValueError, match="There are NaNs in the middle or at the end of exogenous features. Segments with NaNs:"
+    ):
         _ = pipeline.forecast()