diff --git a/python/src/mapreduce/util.py b/python/src/mapreduce/util.py
index <HASH>..<HASH> 100644
--- a/python/src/mapreduce/util.py
+++ b/python/src/mapreduce/util.py
@@ -155,4 +155,8 @@ def create_datastore_write_config(mapreduce_spec):
     operations in the mapreduce.
   """
   force_writes = parse_bool(mapreduce_spec.params.get("force_writes", "false"))
-  return datastore_rpc.Configuration(force_writes=force_writes)
+  if force_writes:
+    return datastore_rpc.Configuration(force_writes=force_writes)
+  else:
+    # dev server doesn't support force_writes.
+    return datastore_rpc.Configuration()
Work around for dev_appserver not supporting force_writes.

Fixes issue <I>