ISR4331 Downgrade

[Smile丶]

I have an ISR4331 running IOS 17.3.4a and Rommon 17.6.2. Now I want to downgrade it to the 16.9 version, but I downloaded several 16.9 IOS, which do not match when verifying the hash value. What's the reason?

Should I need to downgrade the rommon version first? However, this link indicates that the Rommon version cannot be downgraded to the old version since 17.6.1.

Does anyone have any good suggestions

[Smile丶]

the link is here

Cisco 4000 Series ISRs Software Configuration Guide - Installing the Software [Cisco 4000 Series Integrated Services Routers] - Cisco

[balaji.bandi]

You can not downgrade ROMMON once you upgrade, that will not limit for the downgrade IOS.

EDIT

[Smile丶]

Thanks,but the link I post said that can not downgrade to old rommin versions.

Cisco 4000 Series ISRs Software Configuration Guide - Installing the Software [Cisco 4000 Series Integrated Services Routers] - Cisco

[balaji.bandi]

Typo error corrector, yes you can not downgrade ROMMON.

[Smile丶]

So,if I can not downgrade Rommon，wheather I can  downgrade the software from 17.3.4a to 16.9.x?

[Smile丶]

how to solve it，I need to register a PAK license so I want to downgrade the IOS,becanuse the IOS run now only support smart license.

[balaji.bandi]

Let me put this way, ROMMON Downgrade not possible if the device shipped latest version, that will break the system

Iif you have only issue with License, PAK License can be converted in to smart License contract License team

https://community.cisco.com/t5/cisco-software-knowledge-base/smart-license-using-policy-slp/ta-p/4167670

[Smile丶]

So, if Rommon does not downgrade, my IOS cannot be downgraded, right?

[balaji.bandi]

ROMMON Version 17.6.1 is compatible with Cisco IOS XE Releases 16.9 and later.

https://www.cisco.com/c/en/us/support/docs/field-notices/723/fn72304.html

[Smile丶]

However, I downloaded several 16.9 versions of IOS, and each time I verified the Hash value, it did not match. This is strange.

I also tried the 17.3.5 version of IOS, but it still did not match. Is there any solution? By the way, my Rommon version is 17.6.2.

[balaji.bandi]

are you using any proxy. i would avoide install if the hash is not matching.