Lost config after adding a new member to stack

[Jason Flory]

Hello Everyone,

Last weekend I tragically lost the config on a 3850 stack after adding a new stack member.  This happened in latest release 3.3.5.  Steps I took were to upgrade existing stack, upgrade the new switch to be added to 3.3.5.  Cabled in new switch and rebooted stack.  When it came back the only part of the config left were hostname and password.  Interfaces, routing tables, vlan database, access lists were gone and had to be restored from backup.

Has anyone seen this behavior?   It can see losing the entire config but to still have hostname and password present was bizarre.  Also losing the vlan.dat file was also very strange.  You can factory default a switch and still have the vlan.dat file.

I have restored everything and all is well but really want to know why?

Thanks

[Leo Laohoo]

Cabled in new switch and rebooted stack.

If done correctly, the stack should never reboot if you add a new switch to the stack. 

The stack will reboot only when you added a new switch and this new switch is POWER UP.

[Madhukrishnan Gopinathan Nair]

Did you connected the switch POWERED ON ?

Also I see you reloaded the stack after connecting new, why you done that? 

I think you may have not followed the correct procedures of stacking.  I am thinking the new switch would have assumed the role of master switch or something, but i have never seen such a behavior so far.

Thanks,

Madhu