Mostly wondering if other have seen similar abnormalities. And if so, what they found as root cause.
We upgrade about 125 Cisco 9300-48 stacks switches (minority model in our fleet) from 16.12.2 to 17.3.6. During that upgrade we had ~2% of the switches come back online with the 2nd stack switch in default configuration. First thoughts were that someone added the 2nd switch to the stack, configured and forgot to do a write. Going back through backups disproves that theory (multiple writes over several months based on "NVRAM config last update..." message). We do not know if the stratup config was missing the second switch because our first level support fixed the devices prior to anyone looking at the startup config. Various searches have not found anything that seemed to fit.
TIA
