As of October 6 2021, Cisco AnyConnect will be upgraded to version 4.10. You must upgrade to a compatible OS version in order to continue using AnyConnect. If you are upgrading from macOS Sierra or later, macOS Big Sur requires 35.5 GB of available storage to upgrade. If you are upgrading from an earlier release, macOS Big Sur requires up to 44.5 GB of available storage. To upgrade from OS X older then 10.15, first upgrade to OS X El Capitan (version 10.15), and then upgrade to macOS Big Sur if you have enough space.