This document describes how Resource ReserVation Protocol (RSVP) PathErr Messages may be used to trigger rerouting of Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) without first removing LSP state or resources. Such LSP rerouting may desirable in a number of cases including, for example, soft-preemption and graceful shutdown. This document describes the usage of existing Standards Track mechanisms and defines no new formats or mechanisms. It relies on mechanisms already defined as part of RSVP-TE and simply describes a sequence of actions to be executed.