Q:

Cisco AnyConnect VPN Error: "Failed to initialize connection subsystem."

My Cicso AnyConnect VPN client on Windows 7 suddenly started giving the error:

Failed to initialize connection subsystem.

Rebooting didn't help.  How can I resolve this?

A:

The most recent Windows patch-Tuesday update - KB3023607 - causes the same problem with Cisco AnyConnect VPN. Your options for correcting this include:

Follow the instructions listed in Patch Tuesday: KB3023607 Breaks Cisco AnyConnect, Here's a Fix:

On the Windows Taskbar, right-click on the Cisco AnyConnect icon and choose Quit.

Open File Explorer and navigate to: C:\Program Files (x86)\Cisco\Cisco AnyConnect Secure Mobility Client\.
Find vpnui.exe, right-click on it, and then choose the Troubleshoot Compatibility option.

Choose Try Recommended Settings.

Click Test Program (notice that Windows chooses Windows 7 compatibility mode in case you have to set it manually). Choosing to
  "Test the Program" will launch the Cisco AnyConnect client, giving you
  the chance test logging in. It should work.

Once it's proven that Cisco AnyConnect works, choose to save the settings. If it doesn't work, the troubleshooter gives you the options
  of trying again with different settings. The Windows 7 compatibility
  worked for me and I run Windows 8.1.

Program Compatibility Troubleshooter will give you a final report. Close the troubleshooter and you should be good to go.

Apply Windows' "Fix it" solution:

The Fix it solution that's described in this section is not intended
  as a replacement for any security update. We recommend that you always
  install the latest security updates. However, we offer this Fix it
  solution as a workaround for some scenarios. 
To install or remove this Fix it solution, click the Fix it button or
  link under the Enable this fix it heading or the Disable this fix it
  heading. Click Run in the File Download dialog box, and then follow
  the steps in the Fix it Wizard.

Enable this fix it
Disable this fix it

A:

This problem can be caused if Internet Explorer is set to Work Offline mode.

Open IE
Press ALT and click the File menu
Click the Work Offline menu item if it is checked

