diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 6b14dac8dc..8d6acdf2ad 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -933,7 +933,10 @@ async def _extract_form_body(
             assert isinstance(value, sequence_types)
             results: list[bytes | str] = []
             for sub_value in value:
-                results.append(await sub_value.read())
+                if isinstance(sub_value, UploadFile):
+                    results.append(await sub_value.read())
+                else:
+                    results.append(sub_value)
             value = serialize_sequence_value(field=field, value=results)
         if value is not None:
             values[get_validation_alias(field)] = value
diff --git a/tests/test_optional_file_list.py b/tests/test_optional_file_list.py
index a57e6358fd..0e11a262aa 100644
--- a/tests/test_optional_file_list.py
+++ b/tests/test_optional_file_list.py
@@ -26,3 +26,13 @@ def test_optional_bytes_list_no_files():
     response = client.post("/files")
     assert response.status_code == 200
     assert response.json() == {"files_count": 0}
+
+
+def test_optional_bytes_list_send_empty_str():
+    client = TestClient(app)
+    response = client.post(
+        "/files",
+        data={"files": ""},
+    )
+    assert response.status_code == 200
+    assert response.json() == {"files_count": 1, "sizes": [0]}