When the administrator upgraded the Cisco ASA image on the firewalls, it's possible that the new software version is not compatible with the older version of Cisco AnyConnect client installed on the users' devices. Incompatibility between the ASA software image and the client version can result in connection issues.
To resolve this, the administrator should upgrade the Cisco AnyConnect client version to a version that is compatible with the new Cisco ASA software image. This ensures that the client software is able to establish a secure VPN connection with the upgraded ASA firewalls.