license error after upgrading from 11.6.0 HF5 to 13.1.1

Have you verified that the Master Key is the same on the vCMP guest as the UCS archive being loaded? The BIG-IP uses a Secure Vault feature to encrypt certain configuration objects using what is known as Master Key. The Master Key is a password which you can display on the BIG-IP by using the command:

f5mku -K

If you have access to the old device, run that command to identify the Master Key.

Then on the vCMP guest run the following command to change the Master Key:

f5mku - r 

After you have done that, try and load the UCS archive again.

Please check out this article for more details:

K9420: Installing UCS files containing encrypted passwords or passphrases

I hope this helps! 🙂