Cisco ASA 5500 series recommended IOS upgrade path

You might encounter problem while attempt to upgrade Cisco Adaptive Security Appliance (ASA) to Version 8.4.7 or later or to Version 9.1.3 or later. Here is below the recommended upgrade path – that resolves the problem.


ASA version pre-8.3 NAT rule syntax are different than version 8.4 and later. This upgrade path will automatically convert pre-8.3 version NAT rule syntax to version 8.4 and later.

Few well known errors are “”No Cfg structure found in downloaded image file” and “no NAT rule found after the upgrade”.