Cisco Network Convergence System (NCS) 540 Routers with the chassis product ID (PID) N540-24Q8L2DD-SYS will not boot when they are upgraded to Cisco IOS XR Release 7.8.x or 7.9.1. Background Cisco IOS XR releases 7.8.x and 7.9.1 are configured with a specific BIOS version that has...