Issues with stacking 2x3850s.

[inderjit21]

Had issues with upgrade 2x3850 in a stack . Disconnected the stacking cable and was able to upgrade IOS individually. Now when I connect them again with stack cables it not forming the stack.One switch will boot but other is just rebooting giving error.

Message from sysmgr: Reason Code:[4] Reset Reason:Reset/Reload requested by [stack-manager]. [Cable Auth Failed]
get_local: failed: No such file or directory

I have disconnected/reconnected stacking cable twice( brand new cables).

Both switches have same load and ipservices.

[Philip D'Ath]

Which software version are you now running?  Did you use the "software install" command to do the upgrade?

When re-adding the second switch did you try powering it down, and then back up again?

[inderjit21]

Upgraded to 03.06.03E   from 03.02.03 . Yes did software install. Yes connecting stacking cables after shutting down both the switches.

[Philip D'Ath]

Ok, yucky.

Try this:

redundancy
main-cpu
standby console enable

[Philip D'Ath]

If that doesn't work, backup the config, wipe the second switch, power cycle, and try re-joining it to the stack again.

[mlaforest]

Was there a resolution to this?  I am experiencing the same issue.

[hgans]

In my case this was a faulty stack cable.

The reason why this may occur during a software upgrade is,

that the switches in stack issue a "cable auth" process, checking if the cable is a valid and original cisco cable. If this fails, it causes a reboot / boot loop...

[mlaforest]

Same.  Cables were faulty.  RMA'd them and the new ones work perfectly.

[hgans]

same issue here during upgrade to 3.6.4E

FIPS(NGWC): Flash Key Check : Begin
FIPS(NGWC): Flash Key Check : End, Not Found, FIPS Mode Not Enabled
Jun 9 05:21:31 %STACKMGR-1-RELOAD: Reloading due to reason Cable Auth Failed
Jun 9 05:21:31 %IOSXE-3-PLATFORM: process sysmgr: Reset/Reload requested by [stack-manager].

<Thu Jun 9 05:21:31 2016> Message from sysmgr: Reason Code:[4] Reset Reason:Reset/Reload requested by [stack-manager]. [Cable Auth Failed]
get_local: failed: No such file or directory

boot loop since then....