diff --git a/ldclient/impl/datasourcev2/polling_common.py b/ldclient/impl/datasourcev2/polling_common.py
index 532efd9b..b7f9bc28 100644
--- a/ldclient/impl/datasourcev2/polling_common.py
+++ b/ldclient/impl/datasourcev2/polling_common.py
@@ -11,7 +11,8 @@
 from ldclient.impl.datasystem.protocolv2 import (
     DeleteObject,
     EventName,
-    PutObject
+    PutObject,
+    has_unsupported_kind
 )
 from ldclient.impl.util import (
     _LD_ENVID_HEADER,
@@ -68,6 +69,10 @@ def polling_payload_to_changeset(data: dict) -> _Result[ChangeSet, str]:
 
             builder.start(server_intent.payload.code)
         elif event["event"] == EventName.PUT_OBJECT:
+            if has_unsupported_kind(event["data"]):
+                log.debug("Ignoring put-object with unsupported kind: %s", event["data"].get("kind"))
+                continue
+
             try:
                 put = PutObject.from_dict(event["data"])
             except ValueError as err:
@@ -75,6 +80,10 @@ def polling_payload_to_changeset(data: dict) -> _Result[ChangeSet, str]:
 
             builder.add_put(put.kind, put.key, put.version, put.object)
         elif event["event"] == EventName.DELETE_OBJECT:
+            if has_unsupported_kind(event["data"]):
+                log.debug("Ignoring delete-object with unsupported kind: %s", event["data"].get("kind"))
+                continue
+
             try:
                 delete_object = DeleteObject.from_dict(event["data"])
             except ValueError as err:
diff --git a/ldclient/impl/datasourcev2/streaming_common.py b/ldclient/impl/datasourcev2/streaming_common.py
index cb0428d8..903d5438 100644
--- a/ldclient/impl/datasourcev2/streaming_common.py
+++ b/ldclient/impl/datasourcev2/streaming_common.py
@@ -16,7 +16,8 @@
     Error,
     EventName,
     Goodbye,
-    PutObject
+    PutObject,
+    has_unsupported_kind
 )
 from ldclient.impl.util import (
     _LD_ENVID_HEADER,
@@ -65,12 +66,22 @@ def process_message(
         return None
 
     if msg.event == EventName.PUT_OBJECT:
-        put = PutObject.from_dict(json.loads(msg.data))
+        data = json.loads(msg.data)
+        if has_unsupported_kind(data):
+            log.debug("Ignoring put-object with unsupported kind: %s", data.get("kind"))
+            return None
+
+        put = PutObject.from_dict(data)
         change_set_builder.add_put(put.kind, put.key, put.version, put.object)
         return None
 
     if msg.event == EventName.DELETE_OBJECT:
-        delete = DeleteObject.from_dict(json.loads(msg.data))
+        data = json.loads(msg.data)
+        if has_unsupported_kind(data):
+            log.debug("Ignoring delete-object with unsupported kind: %s", data.get("kind"))
+            return None
+
+        delete = DeleteObject.from_dict(data)
         change_set_builder.add_delete(delete.kind, delete.key, delete.version)
         return None
 
diff --git a/ldclient/impl/datasystem/protocolv2.py b/ldclient/impl/datasystem/protocolv2.py
index 7741a216..ce2e1411 100644
--- a/ldclient/impl/datasystem/protocolv2.py
+++ b/ldclient/impl/datasystem/protocolv2.py
@@ -7,6 +7,18 @@
 
 from ldclient.interfaces import EventName, ObjectKind
 
+_SUPPORTED_KINDS = tuple(kind.value for kind in ObjectKind)
+
+
+def has_unsupported_kind(data: dict) -> bool:
+    """
+    Returns True if a put-object or delete-object payload names a kind this
+    SDK does not support. Such objects should be ignored so that new kinds can
+    be added to the protocol without breaking older SDKs.
+    """
+    kind = data.get("kind")
+    return kind is not None and kind not in _SUPPORTED_KINDS
+
 
 @dataclass(frozen=True)
 class DeleteObject:
diff --git a/ldclient/testing/impl/datasourcev2/test_polling_payload_parsing.py b/ldclient/testing/impl/datasourcev2/test_polling_payload_parsing.py
index 8e4c6369..5f9d1676 100644
--- a/ldclient/testing/impl/datasourcev2/test_polling_payload_parsing.py
+++ b/ldclient/testing/impl/datasourcev2/test_polling_payload_parsing.py
@@ -110,6 +110,31 @@ def test_processes_delete_object():
     assert change_set.selector.version == 461
 
 
+def test_ignores_objects_with_unknown_kinds():
+    data = {
+        "events": [
+            {"event": "server-intent", "data": {"payloads": [{"id": "p", "target": 1, "intentCode": "xfer-full", "reason": "payload-missing"}]}},
+            {"event": "put-object", "data": {"version": 1, "kind": "some-future-kind", "key": "unknown-key", "object": {"foo": 1}}},
+            {"event": "put-object", "data": {"version": 1, "kind": "flag", "key": "flag-key", "object": {"key": "flag-key", "version": 1}}},
+            {"event": "delete-object", "data": {"version": 2, "kind": "some-future-kind", "key": "unknown-key"}},
+            {"event": "delete-object", "data": {"version": 3, "kind": "segment", "key": "segment-key"}},
+            {"event": "payload-transferred", "data": {"state": "(p:p:1)", "version": 1}},
+        ]
+    }
+    # Parse a payload that mixes unknown kinds with known flag and segment changes.
+    result = polling_payload_to_changeset(data)
+
+    # The payload completes with only the known changes.
+    assert isinstance(result, _Success)
+
+    change_set = result.value
+    assert [(c.action, c.kind, c.key) for c in change_set.changes] == [
+        (ChangeType.PUT, ObjectKind.FLAG, "flag-key"),
+        (ChangeType.DELETE, ObjectKind.SEGMENT, "segment-key"),
+    ]
+    assert change_set.selector.state == "(p:p:1)"
+
+
 def test_handles_invalid_put_object():
     payload_str = '{"events":[ {"event":"server-intent","data":{"payloads":[ {"id":"5A46PZ79FQ9D08YYKT79DECDNV","target":461,"intentCode":"xfer-full","reason":"payload-missing"}]}},{"event": "put-object","data": {}},{"event":"payload-transferred","data":{"state":"(p:5A46PZ79FQ9D08YYKT79DECDNV:461)","id":"5A46PZ79FQ9D08YYKT79DECDNV","version":461}}]}'
     result = polling_payload_to_changeset(json.loads(payload_str))
diff --git a/ldclient/testing/impl/datasourcev2/test_streaming_synchronizer.py b/ldclient/testing/impl/datasourcev2/test_streaming_synchronizer.py
index 216013b4..1c1fab81 100644
--- a/ldclient/testing/impl/datasourcev2/test_streaming_synchronizer.py
+++ b/ldclient/testing/impl/datasourcev2/test_streaming_synchronizer.py
@@ -295,6 +295,44 @@ def test_handles_delete_objects(events):  # pylint: disable=redefined-outer-name
     assert updates[0].change_set.intent_code == IntentCode.TRANSFER_FULL
 
 
+def test_ignores_objects_with_unknown_kinds(events):  # pylint: disable=redefined-outer-name
+    unknown_put_event = Event(
+        event=EventName.PUT_OBJECT,
+        data=json.dumps({"version": 1, "kind": "some-future-kind", "key": "unknown-key", "object": {"foo": 1}}),
+    )
+    unknown_delete_event = Event(
+        event=EventName.DELETE_OBJECT,
+        data=json.dumps({"version": 2, "kind": "some-future-kind", "key": "unknown-key"}),
+    )
+    builder = list_sse_client(
+        [
+            events[EventName.SERVER_INTENT],
+            unknown_put_event,
+            events[EventName.PUT_OBJECT],
+            unknown_delete_event,
+            events[EventName.DELETE_OBJECT],
+            events[EventName.PAYLOAD_TRANSFERRED],
+        ]
+    )
+
+    synchronizer = make_streaming_data_source()
+    synchronizer._sse_client_builder = builder
+    # Stream a payload that mixes unknown kinds with known flag changes.
+    updates = list(synchronizer.sync(MockSelectorStore(Selector.no_selector())))
+
+    # The payload completes with only the known changes and no error.
+    assert len(updates) == 1
+    assert updates[0].state == DataSourceState.VALID
+    assert updates[0].error is None
+
+    assert updates[0].change_set is not None
+    assert [(c.action, c.kind, c.key) for c in updates[0].change_set.changes] == [
+        (ChangeType.PUT, ObjectKind.FLAG, "flag-key"),
+        (ChangeType.DELETE, ObjectKind.FLAG, "flag-key"),
+    ]
+    assert updates[0].change_set.selector.state == "p:SOMETHING:300"
+
+
 def test_swallows_goodbye(events):  # pylint: disable=redefined-outer-name
     builder = list_sse_client(
         [