@@ -2361,7 +2361,13 @@ def lifecycle_rules(self):
 elif action_type == "SetStorageClass":
 yield LifecycleRuleSetStorageClass.from_api_repr(rule)
 else:
-raise ValueError("Unknown lifecycle rule: {}".format(rule))
+warnings.warn(
+"Unknown lifecycle rule type received: {}. Please upgrade to the latest version of google-cloud-storage.".format(
+rule
+),
+UserWarning,
+stacklevel=1,
+)
 
 @lifecycle_rules.setter
 def lifecycle_rules(self, rules):

@@ -1783,15 +1783,22 @@ def test_iam_configuration_policy_w_entry(self):
 self.assertTrue(config.uniform_bucket_level_access_enabled)
 self.assertEqual(config.uniform_bucket_level_access_locked_time, now)
 
-def test_lifecycle_rules_getter_unknown_action_type(self):
+@mock.("warnings.warn")
+def test_lifecycle_rules_getter_unknown_action_type(self, mock_warn):
 NAME = "name"
 BOGUS_RULE = {"action": {"type": "Bogus"}, "condition": {"age": 42}}
 rules = [BOGUS_RULE]
 properties = {"lifecycle": {"rule": rules}}
 bucket = self._make_one(name=NAME, properties=properties)
 
-with self.assertRaises(ValueError):
-list(bucket.lifecycle_rules)
+list(bucket.lifecycle_rules)
+mock_warn.assert_called_with(
+"Unknown lifecycle rule type received: {}. Please upgrade to the latest version of google-cloud-storage.".format(
+BOGUS_RULE
+),
+UserWarning,
+stacklevel=1,
+)
 
 def test_lifecycle_rules_getter(self):
 from google.cloud.storage.bucket import (