Hi,
Downgrade command only works with moving from Pix v7.x to 6.x
To downgrade from Version 7.2(x) to 7.1.(x), you must perform the following steps:
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Step 1 Load the earlier Version 7.1(x) image
copy tftp flash
IP:
Filename: pix712.bin
Step 2 Reload the device so that it will be use the Version 7.1(x) image.
Step 3 Copy the ASDM Version 5.1(x) image copy tftp flash
IP:
Filename: XXX.bin
Step 4 Enter the following command, this will tell the security appliance where to find the image:
boot system flash:/pix712.bin
asdm image flash:/ asdm file
wr mem
Reload the PIX again and you should be running on 7.1(2)
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Do make sure to take backup of configuration before performing above steps.
Hope this helps.
~Rohit