···1-diff --git a/samcli/local/services/base_local_service.py b/samcli/local/services/base_local_service.py
2-index 7b1ab95895d1..76812f02e00a 100644
3---- a/samcli/local/services/base_local_service.py
4-+++ b/samcli/local/services/base_local_service.py
5-@@ -56,9 +56,11 @@ class BaseLocalService:
6-7- LOG.debug("Localhost server is starting up. Multi-threading = %s", multi_threaded)
8-9-- # This environ signifies we are running a main function for Flask. This is true, since we are using it within
10-- # our cli and not on a production server.
11-- os.environ["WERKZEUG_RUN_MAIN"] = "true"
12-+ # Suppress flask dev server output in a forward-compatible way
13-+ # Source: https://github.com/cs01/gdbgui/issues/425#issuecomment-1119836533
14-+ import flask.cli
15-+
16-+ flask.cli.show_server_banner = lambda *args: None
17-18- self._app.run(threaded=multi_threaded, host=self.host, port=self.port)
19-