diff --git a/litellm/router_utils/handle_error.py b/litellm/router_utils/handle_error.py
index c61a97a9b7..63231923f1 100644
--- a/litellm/router_utils/handle_error.py
+++ b/litellm/router_utils/handle_error.py
@@ -86,7 +86,7 @@ async def async_raise_no_deployment_exception(
         f"No deployment found for model: {model}, cooldown_list with debug info: {_cooldown_list}"
     )
 
-    cooldown_list_ids = [cooldown_model[0] for cooldown_model in _cooldown_list]
+    cooldown_list_ids = [cooldown_model[0] for cooldown_model in (_cooldown_list or [])]
     return RouterRateLimitError(
         model=model,
         cooldown_time=_cooldown_time,
diff --git a/tests/router_unit_tests/test_router_handle_error.py b/tests/router_unit_tests/test_router_handle_error.py
index 39b9814ccc..660b388512 100644
--- a/tests/router_unit_tests/test_router_handle_error.py
+++ b/tests/router_unit_tests/test_router_handle_error.py
@@ -1,6 +1,7 @@
 import sys, os, time
 import traceback, asyncio
 import pytest
+from typing import List
 
 sys.path.insert(
     0, os.path.abspath("../..")
@@ -111,3 +112,147 @@ async def test_send_llm_exception_alert_when_proxy_server_request_in_kwargs():
     # Assert that no exception was raised and the function completed successfully
 
     mock_router.slack_alerting_logger.send_alert.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_async_raise_no_deployment_exception():
+    """
+    Test that async_raise_no_deployment_exception returns a RouterRateLimitError
+    with cooldown_list containing just IDs (not tuples with debug info).
+    """
+    from litellm.router_utils.handle_error import async_raise_no_deployment_exception
+    from litellm.types.router import RouterRateLimitError
+    from unittest.mock import patch
+
+    # Create a mock LitellmRouter instance
+    mock_router = MagicMock()
+    mock_router.get_model_ids.return_value = ["deployment-1", "deployment-2"]
+    mock_router.cooldown_cache.get_min_cooldown.return_value = 30.0
+    mock_router.enable_pre_call_checks = True
+
+    # Mock the _async_get_cooldown_deployments_with_debug_info function
+    # It should return a list of tuples where each tuple contains (model_id, debug_info)
+    mock_cooldown_list = [
+        ("deployment-1", {"error": "rate_limit", "time": "2024-01-01"}),
+        ("deployment-2", {"error": "server_error", "time": "2024-01-01"}),
+        ("deployment-3", {"error": "timeout", "time": "2024-01-01"}),
+    ]
+
+    with patch(
+        "litellm.router_utils.handle_error._async_get_cooldown_deployments_with_debug_info",
+        return_value=mock_cooldown_list,
+    ):
+        # Call the function
+        result = await async_raise_no_deployment_exception(
+            litellm_router_instance=mock_router,
+            model="gpt-3.5-turbo",
+            parent_otel_span=None,
+        )
+
+    # Assert that the function returns a RouterRateLimitError
+    assert isinstance(result, RouterRateLimitError)
+
+    # Assert that the error has the correct properties
+    assert result.model == "gpt-3.5-turbo"
+    assert result.cooldown_time == 30.0
+    assert result.enable_pre_call_checks is True
+
+    # Assert that cooldown_list contains only IDs (extracted from tuples)
+    expected_cooldown_list = ["deployment-1", "deployment-2", "deployment-3"]
+    assert result.cooldown_list == expected_cooldown_list
+
+    # Verify that cooldown_list contains only strings (IDs), not tuples
+    for item in result.cooldown_list:
+        assert isinstance(item, str), f"Expected string ID, got {type(item)}: {item}"
+
+    # Verify mock calls
+    mock_router.get_model_ids.assert_called_once_with(model_name="gpt-3.5-turbo")
+    mock_router.cooldown_cache.get_min_cooldown.assert_called_once_with(
+        model_ids=["deployment-1", "deployment-2"], parent_otel_span=None
+    )
+
+
+@pytest.mark.asyncio
+async def test_async_raise_no_deployment_exception_empty_cooldown_list():
+    """
+    Test that async_raise_no_deployment_exception handles empty cooldown list correctly.
+    """
+    from litellm.router_utils.handle_error import async_raise_no_deployment_exception
+    from litellm.types.router import RouterRateLimitError
+    from unittest.mock import patch
+
+    # Create a mock LitellmRouter instance
+    mock_router = MagicMock()
+    mock_router.get_model_ids.return_value = ["deployment-1", "deployment-2"]
+    mock_router.cooldown_cache.get_min_cooldown.return_value = 15.0
+    mock_router.enable_pre_call_checks = False
+
+    # Mock empty cooldown list
+    mock_cooldown_list: List = []
+
+    with patch(
+        "litellm.router_utils.handle_error._async_get_cooldown_deployments_with_debug_info",
+        return_value=mock_cooldown_list,
+    ):
+        # Call the function
+        result = await async_raise_no_deployment_exception(
+            litellm_router_instance=mock_router,
+            model="claude-3-sonnet",
+            parent_otel_span=None,
+        )
+
+    # Assert that the function returns a RouterRateLimitError
+    assert isinstance(result, RouterRateLimitError)
+
+    # Assert that the error has the correct properties
+    assert result.model == "claude-3-sonnet"
+    assert result.cooldown_time == 15.0
+    assert result.enable_pre_call_checks is False
+
+    # Assert that cooldown_list is an empty list when no cooldowns exist
+    assert result.cooldown_list == []
+    assert isinstance(result.cooldown_list, list)
+
+
+@pytest.mark.asyncio
+async def test_async_raise_no_deployment_exception_none_cooldown_list():
+    """
+    Test that async_raise_no_deployment_exception handles None cooldown list correctly.
+    Note: In practice, _async_get_cooldown_deployments_with_debug_info should never return None
+    based on the implementation, but this tests defensive programming.
+    """
+    from litellm.router_utils.handle_error import async_raise_no_deployment_exception
+    from litellm.types.router import RouterRateLimitError
+    from unittest.mock import patch
+
+    # Create a mock LitellmRouter instance
+    mock_router = MagicMock()
+    mock_router.get_model_ids.return_value = []
+    mock_router.cooldown_cache.get_min_cooldown.return_value = 45.0
+    mock_router.enable_pre_call_checks = True
+
+    # Mock None cooldown list (though this shouldn't happen in practice)
+    mock_cooldown_list = None
+
+    with patch(
+        "litellm.router_utils.handle_error._async_get_cooldown_deployments_with_debug_info",
+        return_value=mock_cooldown_list,
+    ):
+        # After the defensive fix, this should handle None gracefully and return empty list
+        result = await async_raise_no_deployment_exception(
+            litellm_router_instance=mock_router,
+            model="gpt-4",
+            parent_otel_span=None,
+        )
+
+    # Assert that the function returns a RouterRateLimitError
+    assert isinstance(result, RouterRateLimitError)
+
+    # Assert that the error has the correct properties
+    assert result.model == "gpt-4"
+    assert result.cooldown_time == 45.0
+    assert result.enable_pre_call_checks is True
+
+    # Assert that cooldown_list is an empty list when cooldown_list is None
+    assert result.cooldown_list == []
+    assert isinstance(result.cooldown_list, list)