Cisco provides utilities to help migrate configurations from ACS 5.x to ISE, though manual reconfiguration is often recommended for a clean deployment.

. They may be able to provide the file on a case-by-case basis. Cisco Partners : Reach out to a registered Cisco Partner

Once you have obtained the genuine (or base ISO + patches), follow this sequence:

Log into your Cisco active account. If your organization held valid contracts that covered ACS, your portal may still grant access to historical archive downloads.

: For legacy systems where the admin password is lost and the original recovery ISO is missing, some administrators attempt to use newer ISOs (like version 5.8), though compatibility is not guaranteed .