Cisco AnyConnect “Failed to initialize connection subsystem” Error When Connecting to VPN on Windows 7 or Windows 8

I just today I tried to connect to my work network from home using the Cisco AnyConnect client, for reference I’m using AnyConnect 3.1.05182 on Windows 8.1, and was unable to. I was immediately presented with an error before even being asked for a username and password, which said something was wrong with the client, as it hadn’t really had time to start any proper negotiations with the ASA.

A little bit of Googling revealed that the problem might have come from a recent Microsoft update, dated just a few days ago. I had noticed my machine downloading a few updates of late, and I’m nowhere near as diligent with testing updates on my personal machine as I should be, or as I am on any work related systems.

It turns out that this is indeed a bug with the latest set of Microsoft patches, and Cisco confirmed this here.

While Cisco have said ultimately the fix has to come from Microsoft, there is a workaround until a permanent fix is produced;

  • Close the AnyConnect client from the system tray
  • Navigate to the AnyConnect client install location, for example “C:\Program Files (x86)\Cisco\Cisco AnyConnect Secure Mobility Client\”
  • Right click on the vpnui.exe and click troubleshoot compatability
  • Pick “Try recommended settings”
  • Click “Test Program” and this will reopen the AnyConnect client
  • Repeat the same process again, but for vpnagent.exe
  • On the final test when the AnyConnect client opens again, you then find that you’re able to connect normally again. If you have Cisco support it would probably be valuable opening a TAC case and mentioning case number #115021112390273. This bug does also affect Windows 7 when IE11 is installed, and the same fix should work there too.