diff --git a/tests/unit/mocks.py b/tests/unit/mocks.py
index d6ca4b67..24dc9cbc 100644
--- a/tests/unit/mocks.py
+++ b/tests/unit/mocks.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import asyncio
-from aiohttp import ClientResponseError
+from aiohttp import ClientResponseError, RequestInfo
 from datetime import datetime
 from datetime import timedelta
 from datetime import timezone
@@ -214,7 +214,7 @@ def __init__(
     async def _get_metadata(self, *args: Any, **kwargs: Any) -> str:
         instance_uri = f"projects/{self.instance.project}/locations/{self.instance.region}/clusters/{self.instance.cluster}/instances/{self.instance.name}"
         if instance_uri not in self.existing_instances:
-            raise ClientResponseError(None, 404)
+            raise ClientResponseError(RequestInfo(url = instance_uri, method = "GET", headers = None), 404)
         return self.instance.ip_addrs
 
     async def _get_client_certificate(
@@ -226,7 +226,7 @@ async def _get_client_certificate(
     ) -> Tuple[str, List[str]]:
         instance_uri = f"projects/{self.instance.project}/locations/{self.instance.region}/clusters/{self.instance.cluster}/instances/{self.instance.name}"
         if instance_uri not in self.existing_instances:
-            raise ClientResponseError(None, 404)
+            raise ClientResponseError(RequestInfo(url = instance_uri, method = "POST", headers = None), 404)
         root_cert, intermediate_cert, server_cert = self.instance.get_pem_certs()
         # encode public key to bytes
         pub_key_bytes: rsa.RSAPublicKey = serialization.load_pem_public_key(
diff --git a/tests/unit/test_async_connector.py b/tests/unit/test_async_connector.py
index e2b22b10..96e950cf 100644
--- a/tests/unit/test_async_connector.py
+++ b/tests/unit/test_async_connector.py
@@ -19,10 +19,13 @@
 from mocks import FakeAlloyDBClient
 from mocks import FakeConnectionInfo
 from mocks import FakeCredentials
+from mocks import FakeInstance
+from aiohttp import ClientResponseError
 import pytest
 
 from google.cloud.alloydb.connector import AsyncConnector
 from google.cloud.alloydb.connector import IPTypes
+from google.cloud.alloydb.connector.instance import RefreshAheadCache
 
 ALLOYDB_API_ENDPOINT = "https://alloydb.googleapis.com"
 
@@ -294,3 +297,47 @@ async def test_async_connect_bad_ip_type(
             exc_info.value.args[0]
             == f"Incorrect value for ip_type, got '{bad_ip_type}'. Want one of: 'PUBLIC', 'PRIVATE', 'PSC'."
         )
+
+async def test_Connector_remove_cached_bad_instance(credentials: FakeCredentials) -> None:
+    """When a Connector attempts to retrieve connection info for a
+    non-existent instance, it should delete the instance from
+    the cache and ensure no background refresh happens (which would be
+    wasted cycles).
+    """
+    instance_uri = "projects/test-project/locations/test-region/clusters/test-cluster/instances/bad-test-instance"
+    async with AsyncConnector(credentials=credentials) as connector:
+        connector._client = FakeAlloyDBClient(instance = FakeInstance(name = "bad-test-instance"))
+        cache = RefreshAheadCache(instance_uri, connector._client, connector._keys)
+        connector._cache[instance_uri] = cache
+        with pytest.raises(ClientResponseError):
+            await connector.connect(instance_uri, "asyncpg")
+        assert instance_uri not in connector._cache
+
+
+# async def test_Connector_remove_cached_no_ip_type(
+#     fake_credentials: Credentials, fake_client: CloudSQLClient
+# ) -> None:
+#     """When a Connector attempts to connect and preferred IP type is not present,
+#     it should delete the instance from the cache and ensure no background refresh
+#     happens (which would be wasted cycles).
+#     """
+#     # set instance to only have public IP
+#     fake_client.instance.ip_addrs = {"PRIMARY": "127.0.0.1"}
+#     async with Connector(
+#         credentials=fake_credentials, loop=asyncio.get_running_loop()
+#     ) as connector:
+#         conn_name = "test-project:test-region:test-instance"
+#         # populate cache
+#         cache = RefreshAheadCache(conn_name, fake_client, connector._keys)
+#         connector._cache[(conn_name, False)] = cache
+#         # test instance does not have Private IP, thus should invalidate cache
+#         with pytest.raises(CloudSQLIPTypeError):
+#             await connector.connect_async(
+#                 conn_name,
+#                 "pg8000",
+#                 user="my-user",
+#                 password="my-pass",
+#                 ip_type="private",
+#             )
+#         # check that cache has been removed from dict
+#         assert (conn_name, False) not in connector._cache