For issues identified by the vendor, see Cisco Systems' Release Notes for Cisco AnyConnect VPN Client. Many times the VPN auto-installer does not succeed in installing VPN software on the first try due to how the installer looks for certificates and when the site is added to your list of trusted sites. Click retry at least once before giving up. The virtual adapter of Cisco VPN is an internal tool used to get connected to a VPN gateway. As the Cisco VPN client is not compatible with Windows 10, its virtual adapter is failed to be enabled when it tries to be connected to a VPN gateway. So we have to customize this virtual adapter to make Cisco VPN client working in windows 10.

Failed to install AnyConnect Secure Mobility Client 4.8.02042 with installer error: 安装时发生严重错误 (means critical error occurred during installation) A VPN connection cannot be established. When prompted with Windows UAC (User Access Control) you need to allow to install this software. Download the VPN installer from MIT's download page, Cisco AnyConnect VPN Client for Windows. Note: MIT certificates required. The new Cisco AnyConnect VPN client and service will work under Mac OS X (10.6, 10.7, and 10.8), Windows (Vista, Windows 7, and Windows 8, including 64-bit versions), and Linux. Installation and startup are initiated via a web page that installs and launches a signed ActiveX or Java VPN client to connect to MIT's service quickly and easily.

I'm trying to install VPN but I can't continue with the installation because everything is greyed out or only the AMP is available.

This happens when there is a previous installation of VPN on your machine.
First check if it is still installed:

1. From the Finder go to the Application folder.
2. Look for the 'Cisco' folder and open the folder
3. Then double click on 'Uninstall Anyconnect' start uninstall process
4. Follow instructions to uninstall VPN program
5. Reboot
   

If nothing is there here is the procedure for manually uninstalling the AnyConnect client:

Run the following shell script from the Terminal:
$ sudo /opt/cisco/vpn/bin/vpn_uninstall.sh

You will be prompted for your password. Once you enter it, just follow the steps and reboot.

If you are still having problems try this from the terminal.app and reboot:

sudo pkgutil --forget com.cisco.pkg.anyconnect.vpn

Cisco Anyconnect Vpn Client Installation Problems Today

Here is a more detailed page for assistance.

Cisco Anyconnect Vpn Client Installation Problems 2019