Cisco Nexus 9300 bootloop when downgrading from 9.3.5 to 7.0(3)I7(9)

[Emir]

Any ideas what might cause/how to resolve this Nexus 9300 reboot loop:

Issue:
Nexus 93108TC-FX-24
Downgrading from version nxos.9.3.5 to version nxos.7.0.3.I7.9 results in a bootloop.

Our customer got the switches out of the box and wanted to downgrade to the latest 7.x version.
The switches are in factory default setting.

A downgrade from 9.3.5 to 9.3.3 is working well; however a further downgrade from 9.3.3 to 7.x results also in a bootloop.
A downgrade from 9.3.5 to 9.2.1 results in a boot loop as well.

Log:
Last boot messages before the loop starts:

<cut>
Populating conf files for hybrid sysmgr ...
Starting hybrid sysmgr ...
Installing FC2 module using inband eth0 vegas 8 fc2_dom_family 25 ...done
inserting /isan/lib/modules/klm_cisco_nb.o ... done
Executing Prune clis.

MD5:
The MD5 checksum of 7.0.3.I7.9 matches with the one on the Cisco download web site:
Cisco:       d31d5b556cc4d92f2ff2d83b5df7b943
Customer: d31d5b556cc4d92f2ff2d83b5df7b943

Furthermore, the same 7.x file works well on my lab switch.

Affected:
Reproducible on 2 switches.

Workaround:
Breaking bootloop bij booting to boot loader and loading the original image resolves the bootloop (but keeps the 9.3 version):
loader > boot bootflash:nxos.9.3.5.bin

Troubleshooting:
Booting from USB or TFTP to 7.0.3.I7.9 or 7.0.3.I7.8 results in a bootloop as well.
The same 7.0.3.I7.9 file works well on one of my lab switches, where I can downgrade from 9.3.5 directly to 7.0.3.I7.9 without a bootloop.

cmdline recoverymode = 1
init system
format bootflash
and then trying to boot only works with the 9.3.5 version; with the 7.x version I end up in a bootloop again.

Does anyone know how to resolve this/downgrade successfully to 7.0.3.I7.9?

[Christopher Hart · Accepted solution]

Hi Emir!

Unfortunately, the Nexus 93108TC-FX-24 is not supported in the NX-OS 7.0(3)I7(x) software train (including the latest maintenance release in that train, NX-OS software release 7.0(3)I7(9)). This model of switch is not listed as supported hardware in the NX-OS 7.0(3)I7(9) software release notes. Under the "Product Specifications" section of the data sheet for the Nexus 93108TC-FX-24, the minimum NX-OS software release is listed as NX-OS 9.3(2) or later.

I recommend upgrading this switch from NX-OS software release 9.3(5) to NX-OS software release 9.3(6) prior to production - The NX-OS 9.3(x) software train is the upcoming long-lived release (compared to the current long-lived release of 7.0(3)I7(x)).

I hope this helps - thank you!

-Christopher