Unexpected exceptions in WfMS are situations not predicted during the design phase. Human involvement in handling this type of exceptions has been recognized to be a crucial factor. We developed a framework to support the user in handling these situations by redesigning the flow, ad hoc executing the affected tasks, and manipulating engine status. A good characterization of the exception is needed to help the user identifying the best executable solution. The proposed characterization results from integrating operational, tactical and strategic perspectives over unexpected exceptions. An open source platform was selected to establish a test base on which the framework will be tested.