From 7d4375fc6adf7a155e48605e2863901a031ff8dc Mon Sep 17 00:00:00 2001
From: Shunping Huang <shunping@google.com>
Date: Wed, 26 Feb 2025 11:15:12 -0500
Subject: [PATCH] Fix the case when update_compatibility_version is used
 without argument.

---
 sdks/python/apache_beam/options/pipeline_options.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sdks/python/apache_beam/options/pipeline_options.py b/sdks/python/apache_beam/options/pipeline_options.py
index 8eba11d9ea34..775f73bd2afd 100644
--- a/sdks/python/apache_beam/options/pipeline_options.py
+++ b/sdks/python/apache_beam/options/pipeline_options.py
@@ -591,6 +591,8 @@ def _add_argparse_args(cls, parser):
     parser.add_argument(
         '--update_compatibility_version',
         default=None,
+        nargs='?',
+        const=None,
         help='Attempt to produce a pipeline compatible with the given prior '
         'version of the Beam SDK. '
         'See for example, https://cloud.google.com/dataflow/docs/guides/'