Bootloop C3850XS in VSS configuration how to disable VSS from boot prompt running IOS XE 16.6.1

[cco_heerema]

During a setup of my new cores (2 x 3850 XS switches) running IOS XE 16.6.1 in VSS mode due to an unknown reason one of my switches keeps rebooting after switch election with the following message :

Waiting for 120 seconds for other switches to boot
#######################################################################################################################
Switch number is 2

Chassis 2 reloading, reason - Active/standby selection failed in 1+1 Mode
Oct 2 14:08:18.652 FP0/0: %PMAN-5-EXITACTION: Process manager is exiting: reload fp action requested
Switch rebooted continously for atleast 5 times. Disabling autoreboot
Oct 2 14:08:23.557 RP0/0: %PMAN-5-EXITACTION: Process m
octeon_wdt: WDT device closed unexpectedly. WDT will not stop!
reboot: Restarting system

I have tried to boot without the startup config (as used in the password recovery), and many other things including the full emergency recovery which erases the boot flash: but no success.

Switch refuses to do anything else than looping with the message above.

The other switch is available, and I had a succesfull setup with VSS but again with an unknown reason I found this morning the switch in a continues boot.

As the IOS is recent, I cannot find anything on the web how to solve this issue (VSS is a recent added option to this hardware platform) so any tips on completely factory default my 3850XS or removing / bypasing the VSS stack election would be great !

[Reza Sharifi]

Is there a mode button on the model? If yes, hold it down for about 10 seconds and that should put the device into factory default, if not RMA to Cisco, use IOS 03.06.06.E.152-2.E6.bin for now.

HTH

[cco_heerema]

The mode button does not work other than getting the bootloader prompt. (that's how I was able to do the recover procedures) I could try to downgrade it to a 3 version, is that what you are suggesting ?

RMA is a final resort, so hoping for a "soft" solution here, and as my design is VSS based downgrading to a 3 version is not an option (VSS is not supported), Cisco presales promised me VSS is supported and stable. 

Hoping on a soft sollution / someone who experienced and solved this I created this topic.
If worse comes to worse I will create a TAC case for eventualy a RMA procedure.

[cco_heerema]

So for future reference if any ony finds this .. here is the sollution to get your switch out of the boot loop :

in bootloader mode  enter :

Switch: set

you will see outout like below (values may vary)

        switch: set

      ABNORMAL_RESET_COUNT=0

        ASIC_PCI_RESET=1

        AUTOREBOOT_RESTORE=1

        BOOT=flash:packages.conf

        BOOT_LOADER_UPGRADE_DISABLE=1

        BSI=0

        CFG_MODEL_NUM=WS-C3650-48TQ-L

        CLEI_CODE_NUMBER=IPMWC00ARE

        CSR_PCIERST_DISCONNECTED=yes

        DC_COPY=yes

        D_STACK_DOMAIN_NUM=1

        ECI_CODE_NUMBER=469509

        LICENSE_BOOT_LEVEL=lanbasek9,all:ngwc;

        MAC_ADDR=40:01:7A:F4:35:00

        MANUAL_BOOT=yes

        MODEL_NUM=WS-C3650-48TQ

        MODEL_REVISION_NUM=Q0

        MOTHERBOARD_ASSEMBLY_NUM=73-15902-05

        MOTHERBOARD_REVISION_NUM=A0

        MOTHERBOARD_SERIAL_NUM=FDO21252AMQ

        RANDOM_NUM=131611057

        RECOVERY_BUNDLE=sda9:cat3k_caa-recovery.bin

        STACK_1_1=3_0                                                                                           !!!!!!!!!!!!

        SWITCH_IGNORE_STARTUP_CFG=1

        SWITCH_NUMBER=1

        SWITCH_PRIORITY=15

        SYSTEM_SERIAL_NUM=FDO2126V05E

        TAN_NUM=800-41241-03

        TAN_REVISION_NUMBER=C0

        TEMPLATE=advanced

        TERMLINES=0

       VERSION_ID=V04

issue

         switch: STACK_1_1=0_0

boot manually the switch which fails to boot:

Switch:boot

I was able to boot again and log in than I did :

switch clear stack-mode

removed the Virtual stackwise domain :

no stackwise-virtual 

And to be sure I reloaded and did a wr erase after that and another reload.

Long story short DO NOT USE  IOS XE 16.6.1.

[aaron.perez]

I had the exact same issue with a Catalyst 9500-12Q. However, the stack variable on that model is read-only. If you try to set the variable to something different, it kicks back "variable is write protected"

I was able to just unset those variables for the stack configuration and it booted normally again.

[jonathanpumida1]

We are currently having this issue using 16.6.6 for 3850 stacked switch. Any advise?

[dongcheng xu]

Really really helpful, thank you

[mohammed-islam12]

Thanks - this procedure works for me very well.

[aabuzahr]

you can refer to this document, since 9k and 3850 are so similar
https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-series-switches/212912-catalyst-9000-switches-booting-to-switch.html

[aabrams]

I had the exact same problem.

Chassis 3 reloading, reason - Active/standby selection failed in 1+1 Mode

Here is the fix....

!--- From the 'switch:' prompt, issue 'set'
set
!--- You'll notice the from the output 'STACK_1_1=2_0'
!--- change this to 'STACK_1_1' by issuing 'unset STACK_1_1' and then 'boot'
unset STACK_1_1
boot
!--- now the switch boots normal