diff --git a/python/ray/__init__.py b/python/ray/__init__.py
index e689eb9fc..d05aa6d9e 100644
--- a/python/ray/__init__.py
+++ b/python/ray/__init__.py
@@ -51,8 +51,8 @@ from ray.profiling import profile  # noqa: E402
 from ray.worker import (error_info, init, connect, disconnect, get, put, wait,
                         remote, get_gpu_ids, get_resource_ids, get_webui_url,
                         register_custom_serializer, shutdown)  # noqa: E402
-from ray.worker import (SCRIPT_MODE, WORKER_MODE, LOCAL_MODE,
-                        SILENT_MODE)  # noqa: E402
+from ray.worker import (SCRIPT_MODE, WORKER_MODE, LOCAL_MODE, SILENT_MODE,
+                        PYTHON_MODE)  # noqa: E402
 from ray.worker import global_state  # noqa: E402
 # We import ray.actor because some code is run in actor.py which initializes
 # some functions in the worker.
@@ -67,8 +67,8 @@ __all__ = [
     "error_info", "init", "connect", "disconnect", "get", "put", "wait",
     "remote", "profile", "actor", "method", "get_gpu_ids", "get_resource_ids",
     "get_webui_url", "register_custom_serializer", "shutdown", "SCRIPT_MODE",
-    "WORKER_MODE", "LOCAL_MODE", "SILENT_MODE", "global_state", "ObjectID",
-    "_config", "__version__"
+    "WORKER_MODE", "LOCAL_MODE", "SILENT_MODE", "PYTHON_MODE", "global_state",
+    "ObjectID", "_config", "__version__"
 ]
 
 import ctypes  # noqa: E402
diff --git a/python/ray/worker.py b/python/ray/worker.py
index 488283c55..d00c28dda 100644
--- a/python/ray/worker.py
+++ b/python/ray/worker.py
@@ -44,6 +44,7 @@ SCRIPT_MODE = 0
 WORKER_MODE = 1
 LOCAL_MODE = 2
 SILENT_MODE = 3
+PYTHON_MODE = 4
 
 ERROR_KEY_PREFIX = b"Error:"
 DRIVER_ID_LENGTH = 20
@@ -1574,6 +1575,9 @@ def _init(address_info=None,
         Exception: An exception is raised if an inappropriate combination of
             arguments is passed in.
     """
+    if driver_mode == PYTHON_MODE:
+        raise Exception("ray.PYTHON_MODE has been renamed to ray.LOCAL_MODE. "
+                        "Please use ray.LOCAL_MODE.")
     if driver_mode not in [SCRIPT_MODE, LOCAL_MODE, SILENT_MODE]:
         raise Exception("Driver_mode must be in [ray.SCRIPT_MODE, "
                         "ray.LOCAL_MODE, ray.SILENT_MODE].")