diff --git a/sdk/python/feast/infra/offline_stores/duckdb.py b/sdk/python/feast/infra/offline_stores/duckdb.py
index 1ff09d9f3cf..ebca2245d46 100644
--- a/sdk/python/feast/infra/offline_stores/duckdb.py
+++ b/sdk/python/feast/infra/offline_stores/duckdb.py
@@ -95,6 +95,13 @@ def _read_data_source(data_source: DataSource, repo_path: str) -> Table:
         if storage_options:
             return ibis.read_delta(data_source.path, storage_options=storage_options)
         return ibis.read_delta(data_source.path)
+    else:
+        raise ValueError(
+            f"Unable to determine the file format for data source "
+            f"'{data_source.name}' with path '{data_source.path}'. Either set "
+            f"'file_format' explicitly on the FileSource (e.g. ParquetFormat()) "
+            f"or use a path with a recognized file extension (e.g. '.parquet')."
+        )
 
 
 def _read_iceberg_catalog_source(data_source: "IcebergSource", repo_path: str) -> Table:
diff --git a/sdk/python/tests/unit/infra/offline_stores/test_duckdb.py b/sdk/python/tests/unit/infra/offline_stores/test_duckdb.py
new file mode 100644
index 00000000000..1ed46279a8b
--- /dev/null
+++ b/sdk/python/tests/unit/infra/offline_stores/test_duckdb.py
@@ -0,0 +1,15 @@
+import pytest
+
+from feast.infra.offline_stores.duckdb import _read_data_source
+from feast.infra.offline_stores.file_source import FileSource
+
+
+def test_read_data_source_raises_on_unresolvable_file_format():
+    data_source = FileSource(
+        name="driver_hourly_stats_source",
+        path="data/driver_stats.csv",
+        timestamp_field="event_timestamp",
+    )
+
+    with pytest.raises(ValueError, match="Unable to determine the file format"):
+        _read_data_source(data_source, repo_path=".")