The Exception Handler element defines the group of operations to carry out when an exception occurs. In an Activity diagram, the protected element can contain a set of operations and is connected to the exception handler via an Interrupt Flow connector. Any defined error contained within an element's parts can trigger the flow to move to an exception.
OMG UML Specification:
The OMG UML specification (UML Superstructure Specification, v2.1.1, p.364) states:
An exception handler is an element that specifies a body to execute in case the specified exception occurs during the execution of the protected node.