Abstract: Methods and associated structure for on the fly (dynamic) transition between versions among a management application process and an associated I/O subsystem. A management application program operable on a management system coupled to the I/O subsystem instantiates a script engine to execute script language commands for communicating with the I/O subsystem on behalf of the management application. The particular script engine instantiated is one that is compatible with the present revision of firmware operable in the I/O subsystem. When a script command execution causes a firmware upgrade in the I/O subsystem, the present script engine saves its state of operation, notifies the management application of the upgrade and resultant incompatibility and terminates. The management application then instantiates a new script engine compatible with the newly upgraded firmware version in the I/O subsystem.