Abstract: The present invention discloses a solution for check-stopping firmware implemented virtual communication channels without disabling all firmware functions. In the solution, a virtual input/output subsystem of firmware can be selectively isolated from other portions of the firmware. This permits the virtual input/output subsystem to be disabled when severe errors occur involving virtual communication channels, without affecting other portions and functions of the firmware. Check-stopping the virtual I/O subsystem can be performed using existing hardware mechanisms for handling permanent errors including channel report words (CRW), channel control block (CHCB), and the like. The subsystem can be reactivated in response to a firmware patch which can be an automated or manual procedure.