2018-12-31 00:49:40.025 59372 ERROR mistral.notifiers.default_notifier Exception: [9ad86428-59ca-4823-87ad-61915f61410d] Unable to publish event because st2 returned status code 500. {

2018-12-31 00:49:40.025 59372 ERROR mistral.notifiers.default_notifier "faultstring": "Internal Server Error"

2018-12-31 00:49:40.025 59372 ERROR mistral.notifiers.default_notifier }

2018-12-31 00:49:40.025 59372 ERROR mistral.notifiers.default_notifier

Bug also raised for more details - https://bugs.launchpad.net/mistral/+bug/1808668