diff --git a/endpoints/common.py b/endpoints/common.py
index 1dbb2ab77..61051237e 100644
--- a/endpoints/common.py
+++ b/endpoints/common.py
@@ -91,13 +91,13 @@ def common_login(db_user):
 @app.errorhandler(model.DataModelException)
 def handle_dme(ex):
   logger.exception(ex)
-  return make_response('Internal Server Error', 500)
+  return make_response(ex.message, 400)
 
 
 @app.errorhandler(KeyError)
 def handle_dme_key_error(ex):
   logger.exception(ex)
-  return make_response('Internal Server Error', 500)
+  return make_response('Invalid key: %s' % ex.message, 400)
 
 
 def generate_csrf_token():