I had the below afer the module failed, but before we did the hot swap. The "Nonstop switching is not support" message I'd not fully considered before - I assumed it was related to the failed module and it couldn't determine the SW version in use, but I guess the more likely cause is that the two modules were indeed running different firmware versions.
Given we were replacing MM2 - the failed unit - I'd still not have expected it to reboot though when replacing the module.
>show redundancy
Configured Mode: Nonstop Switching
Current Mode : Warm Standby
*Nonstop switching is not supported with different SW versions in MM1 and MM2.
Rapid Switchover Stale Timer : 90
Failovers : 0
Last Failover :
Slot Module Description State SW Version Boot Image
---- ---------------------------------------- -------- ------------- ----------
MM1 HP J9827A Management Module 5400Rzl2 Active KB.16.03.0003 Primary
MM2 Failed