No Cfg structure found in downloaded image file

尝试把ASA5512从9.1.1升级9.12.4版本，每次从ASDM的文件管理界面上传固件都报错，接着尝试用命令行tftp升级，等文件传输完毕，最后显示错误”No Cfg structure found in downloaded image file“

然后上网搜了一下，原来是因为后面从9.1.3的固件版本结构改动了，要升级到特定的版本才能直接升级最新的，参看页面如下：

https://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/116685-problemsolution-product-00.html

Introduction

This document describes a problem encountered when you attempt to upgrade the Cisco Adaptive Security Appliance (ASA) to Version 8.4.7 or later or to Version 9.1.3 or later. It also provides the upgrade path that resolves the problem.

Problem

When you attempt an ASA upgrade to these versions:

you receive this error message: 

No Cfg structure found in downloaded image file

This error message is generated because the file structure for the ASA binary images changed in both Version 8.4.7 and Version 9.1.3. There is a specific upgrade path you must follow.

Solution

Follow this version upgrade process:

  1. Locate your current version in the Current ASA Image column.
  2. Upgrade to the version listed in the First Upgrade column.
  3. Upgrade to one of the versions listed in the Final Upgrade column:
Current ASA Image First Upgrade Final Upgrade
8.2.x 8.4.6 8.4.7 or later, 9.1.3 or later
8.3.x 8.4.6 8.4.7 or later, 9.1.3 or later
8.4.1 through 8.4.4.10 8.4.6, 9.0.2 8.4.7 or later, 9.1.3 or later
8.5.x 9.0.2 9.1.3 or later
8.6.1 9.0.2 9.1.3 or later
9.0.1 9.0.2 9.1.3 or later
9.0.1.1 and later
(to include 9.0.2 and later) 		Not Applicable 9.1.3 or later
9.1.1 9.1.2 9.1.3 or later
9.1.1.1 and later Not Applicable 9.1.3 or later

看完参考资料，去找了个9.1.2的版本load上去就没有报错了。
固件下载地址：http://www.hostwaydcs.com/CISCO/Legacy/old/asa912-smp-k8.bin