If an Automatic Activity fails the Process Execution Engine can be configured to retry the Activity.
The Engine will try to execute it as many times as defined in the Engine properties Retry times and Retry interval. If the execution is still not successful, then an exception is thrown.
If an action within the Automatic activity has not completed and needs to be reverted, you must manually define the rollback in an Exception Handling Flow for that Automatic activity. The best way to implement the rollback is to define an Exception Flow for each possible known exception. Therefore the Automatic activity will have multiple exception transitions, one for each known exception that might occur. To contain all other not expected exceptions, design the Exception Flow for the Others exception.