Irule error unable to upgrade image

Try to use "!" instead of "not eq"

    {!([class match [IP::client_addr] equals private_net])}

Check whether the iRule is in use. If not, delete it prior to upgrade

To add to the previous posts also private_net may need to be $private_net or "private_net" or "$private_net" but if it is not used remove it as the new f5 version may better detect the bad config than the old one.