Try cleaning up/removing some residual keys in the registry that the OS failed to remove or update when the last installation ran.
- Residual registry entries are intentionally left behind as part of the AnyConnect un/installer architecture.
- Unfortunately, sometimes these residual entries get corrupted, preventing the installation from progressing.
- This is not version-specific and not an Cisco issue but an OS un/installation issue that is acknowledged by Microsoft, who has written a tool to address these sorts of problems.
- The tool can be run on the machine to fix the corrupted registries.
https://support.microsoft.com/en-us/topic/fix-problems-that-block-programs-from-being-installed-or-removed-cca7d1b6-65a9-3d98-426b-e9f927e1eb4d
Path:
-Download Toubleshooter Tool > Uninstalling > Cisco Secure Client - AnyConnect VPN
- Several times this tool to be useful and then reboot the machine after.
- Try a fresh install after that tool and reboot have been completed.