Advanced Notice: Host Scan updates for AnyConnect 4.3 and earlier will cease to exist after December 31 2018. All Host Scan updates will be provided via the Host Scan 4.6 and later module which is compatible with AnyConnect 4.4.x and later with up ASDM (ASA Device Manager) 7.9.2 and later. Please review the AnyConnect Release Notes and AnyConnect Host Scan 4.3 to 4.6.x Migration Guide for further details.
https://www.cisco.com/c/en/us/td/docs/security/asa/migration/guide/HostscanMigration43x-46x.html
