9500-40X ISSU upgrade procedure 16.9.6

[M1LEN]

Hello team,

I have a problem with the Cisco guides and releases for hte upgrade procedure (ISSU) for 9500 from 16.9.3 to 16.9.6. 
It is a stackwise virtual cluster and I see following info:

In this guide :

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9500-series-switches/214406-in-service-software-upgrade-issu-on-ca.html

We have the two ways to run ISSU upgrade, which is fine.

On the below release notes for 16.9.X  it says as example only 16.9.2 to 16.9.3 requires the SMU installation.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-9/release_notes/ol-16-9-9500.html#task_td3_gwl_2hb

Following the other guide it looks like SMU is still required. Here it is misleading whether for 9500-40X  from 16.9.3 to 16.9.6 we have SMU requirement or not

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst_standalones/b-in-service-software-upgrade-issu.html

So my question is whether I need SMU package installation or not - if yes, which. 
Hope someone has already gone through this upgrade and can share how to do the in-service-upgrade.

Thanks

Milen 

[Leo Laohoo]

Install the SMU only when it is necessary. 

WARNING:  Do not believe the "HITLESS" description.  Some SMU for the Catalyst 9500 will reboot the appliance simultaneously.

[M1LEN]

The ISSU upgrade failed. It installed on standby succesfully, after booting and completing the SSO, the Active didn't proceed with the install... I involved TAC and they used some internal commands to stop the process and then manually upgrade the Active and rebooted it. 

I have few other 9500-40X to upgrade but will not use this ISSU for sure....

I will leave this open - if someone wants to add/comment more :)\

Cheers

Milen