Will ISR4321/K9 Rommon Version 16.12(2r) work with IOS 16.09.03

[scottsassin]

Will the above router work with the above rommon version and IOS version, or do I need to downgrade the rommon or upgrade to a later IOS? 

[balaji.bandi]

You have both the Option and upgrade and the downgrade depends on the requirement.

if you have 16.12.X ROMMON installing 16.12.X IOS XE is a good option, but make sure you read the release notes and requirements.

as per Cisco 17.3.3 or 17.3.4 is good version, again what kind of RAM device has also important before upgrade :

you can find the ROMMON Matrix with support IOS XE below :

https://www.cisco.com/c/en/us/td/docs/routers/access/4400/software/configuration/xe-16-12/isr4400swcfg-xe-16-12-book/installing_the_software.html

[Leo Laohoo · Accepted solution]

Yes, 16.12(2r) will work with 16.9.X.