---
features:
  - |
    A new ``traceback`` field has been added to each versioned instance
    notification. In an error notification this field contains the full
    traceback string of the exception which caused the error notification.
    See the `notification dev ref`_ for the sample file of
    ``instance.create.error`` as an example.

    .. _notification dev ref: https://docs.openstack.org/nova/latest/reference/notifications.html#existing-versioned-notifications
