Using gcloud app deploy to deploy to App Engine will fail if cron.yaml or cron.xml contains timezone information, when run using Cloud SDK 297.0.0.
For example:
[INFO] GCLOUD: ERROR: (gcloud.app.deploy) An error occurred while parsing file: [/path/to/file/cron.yaml]
[INFO] GCLOUD: Unable to assign value 'America/New_York' to attribute 'timezone':
[INFO] GCLOUD: timezone 'America/New_York' is unknown