9800-L WLC OS Upgrade

[cupkeyk]

Hello, 

I have a new 9800-L that I'm trying to OS upgrade.

Default is 17.03.04c and my target OS is 17.9.3 , I've tried directly upgrading it to that OS but encountered issue terminating the upgrade, since there is a big difference in OS version I tried doing a ladder approach to upgrade the OS with the version 17.03.07 but still encountered the same issue. 

issue mainly : Not supported 

I checked some existing WLCs that have the same version, so I'm wondering what causes this issue and what other troubleshooting I can do. 

Reference docs that I also utilized : https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/217050-convert-installation-mode-between-instal.html 

[Leo Laohoo]

There are two ways to upgrade the WLC (Install Mode).  

The first way, the Cisco recommended approach, means the WLC will automatically reboot after the Install Mode command is entered (refer to Cisco ISR & ASR 1k Routers: IOS-XE/Firmware Upgrade (Install Mode)).

The second method is what I call as the one-hit-wonder.  With this method, the WLC will not reboot and will require the operator to use the "reload" command.  Very useful if there is the need to reboot the WLC at a later time/date.

[marce1000]

              >....but encountered issue terminating the upgrade,
 - Post exact outputs and or error messages as they are  being observed ,

 M.

[Rasika Nayanajith]

Read the release notes carefully, there may be some incompatible configuration lines on your existing configuration. In release notes those things will be documented.

Here are some important notes I can see in 17.9.3 release notes

• ISSU feature is supported only within and between major releases, for example, 17.3.x (within a release) and 17.3.x to 17.6.x (among major releases).

• Controller upgrade from Cisco IOS XE Bengaluru 17.3.x to Cisco IOS XE Bengaluru 17.6.x or Cisco IOS XE Cupertino 17.9.x or later using ISSU may fail if the domain command is configured. Ensure that you run the no domain command before starting an ISSU upgrade because the domain command has been removed from Cisco IOS XE Bengaluru 17.6.x.

• Controller upgrade from Cisco IOS XE Bengaluru 17.3.x to any release using ISSU may fail if the snmp-server enable traps hsrp command is configured. Ensure that you remove the snmp-server enable traps hsrp command from the configuration before starting an ISSU upgrade because the snmp-server enable traps hsrp command has been removed from Cisco IOS XE Bengaluru 17.4.x.

• Rolling AP upgrade, which is a part of the ISSU feature, is not supported for mesh APs.

HTH
Rasika
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[Rich R]

Like Marce said post the exact commands you used and the exact output you got from the WLC up to and including the error message. 
And always refer to the relevant release notes as Rasika has pointed out because there are often known caveats and restrictions which you need to be mindful of.  
And make sure the ROMMON and PHY firmware are up to date as per
https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/214749-tac-recommended-ios-xe-builds-for-wirele.html#toc-hId--255704749