1. A method of error recovery in a replicated state machine, wherein, at a defined time in an operation of the machine, a batch of inputs are input to the machine, and the machine uses a multitude of components for processing said inputs, and wherein during said processing, one of said components generates an exception, the method comprising the steps of: after the exception, rolling the state machine back to a defined point in the operation of the machine; preemptively failing said one of the components; re-executing the batch of inputs in the state machine; handling any failure, during said re-executing step, of said one of the components using a defined error handling procedure; and repeating the rolling, preemptively failing, re-executing and handling steps until the input batch runs to completion without generating any exception in any of the components that are not pre-emptively failed.